bluuebunny/crossref_metadata_2025 huggingface dataset:
METHODS FOR THE PHOTO‐ELECTRIC AND PHOTO‐CHEMICAL MEASUREMENT OF DAYLIGHT1
Authors: ATKINS W. R. G. , POOLE H. H.
Published: January 2008

The optical conditions relating to plane, cylindrical, and spherical photometers are discussed.

A brief account is given of some galvanometers found to be suitable for the measurement of the photo‐electric current in the field, of the potentiometer method for use at sea, and of the use of a recording galvanometer for continuous measurement of the variations of daylight. The current may be integrated over a short period by timing the flashes of a neon lamp shunted by a condenser, or, over longer periods, by the electrolytic deposition of copper.

Types of photo‐electric cells are discussed in relation to their spectral sensitivity, constancy and standardisation.

Examples are given of photo‐electric measurements of daylight in the open, in buildings, in woods, and down to 70 metres depth in the open sea.

A brief description is given of photo‐chemical photometry by means of uranyl oxalate solutions and its standardisation against photo‐electric measurements. The methylene blue method of ultra‐violet photometry is also mentioned.
Virus Diseases In Plants:I. TRANSLOCATION WITHIN THE PLANT. II. THE AMOEBOID INTRACELLULAR INCLUSIONS.
Authors: SMITH J. HENDERSON
Published: January 2008

Summary.

In virus disease in plants, abnormal inclusions, found only in such disease, are frequently found inside the cells. Of these inclusions one type has characters which have led to the belief that it may be a living amoeba‐like organism, a phase in the life‐history of the virus parasite. This type, the “X‐body,” is fully described and the evidence for its parasitic nature set out. The alternative view is that these bodies are not living organisms but are a reaction‐product of the cell to the virus irritant. This seems, on the whole, more probable, and is supported by some recent work in which formation of the bodies has been watched in the individual cell from their beginning to their completion, the method of formation accounting for the appearances which have suggested that the bodies are independent organisms.
THE BIRD FAUNA OF THE GALAPAGOS ISLANDS IN RELATION TO SPECIES FORMATION
Authors: SWARTH HARRY S.
Published: January 2008

The Galapagos Islands possess a peculiar and highly characteristic fauna and flora. The abundant bird and reptile populations are nearly all of endemic species; of the land birds only two species occur elsewhere than in these islands. Studies bearing upon the origin of the Galapagos fauna have led to diverse conclusions; scrutiny of modes of variation has revealed some curious situations. The Galapagos have been variously regarded as the surviving remnants of a land‐mass, now sunken, that was formerly connected with the American mainland, and as oceanic islands that have appeared above the ocean as the result of volcanic upheaval. Study of the birds is confirmatory of the latter view. The avifauna is clearly not derived from the South American mainland directly to the eastward. Of the marine species there are one or two of southern origin, borne northward on the cold Humboldt current, and there are others which constitute local forms of species that are of world‐wide distribution. There is an important element definitely recognisable as of West Indian derivation, and others may have originated from the same source. There are a few species that clearly are not of West Indian ancestry, and there are a number that are too widely differentiated for recognition of their immediate affinities. The hypothesis is advanced that the inception of the Galapagos avifauna took place in a period when North and South America were separated by the sea; the relationship of the faunas of the West Indies and the Galapagos is to be regarded in the same light as relationships from one to another of the West Indian islands. The bird population of the Galapagos, abundant as regards individuals, is, as regards representation of different groups, of the sparse and miscellaneous character to be expected of chance‐controlled wanderers to distant islands.

Conditions are uniform enough throughout the archipelago, so that, with much local variation, each island contains a fair representation of the same general assemblage of species. Trends of variation are seen in arrested stages of plumage in certain species, in a possible tendency to melanism in others. There are many variants of these situations. The outstanding group of birds is the endemic family, the Geospizidae, including 37 species and sub‐species out of the entire list of 89 breeding birds. Extensive variation and complicated relationships within this family are such as can probably not be duplicated in any mainland stock of birds. The observed variation presents difficulties to classification, and certain trends of development seem to act independently of natural selection. The Geospizidae afford a fine example of diversification unhindered by competition.
THE PROTEOLYTIC ENZYMES OF MICRO‐ORGANISMS
Authors: HAINES R. B.
Published: January 2008

The formation of exo‐enzymes may be shown in the case of bacteria by centrifuging off the organisms, with or without filtration, through a suitable filter candle or Seitz asbestos filter, and incubating with the appropriate substrate at the required pH. Further concentration and purification may be carried out by evaporation in vacuo at low temperatures (Hladik, 1910), fractional precipitation with ammonium sulphate (London and Pakhotina, 1917), precipitation, dialysis and re‐precipitation with alcohol (Munter, 1910), adsorption on alumina or kaolin and fractional elution with suitable buffers of selected pH (Willstätter, 1928; Hopkins, 1930), dialysis (Harden and Young, 1906; Walter, 1917), and extracting with glycerine (Macfadyen, 1892).

With moulds and actinomycetes the mycelium may be filtered off through paper and suitable methods of concentration applied to the filtrate. For the preparation of endo‐enzymes of bacteria, autolysis may be used, alternative freezing and thawing (Young, 1929), grinding in an agate mortar (Stevens and West, 1922, a, b), or lysis with bile (Avery and Cullen, 1923). For yeasts and fungi the “acetone‐dauerhefe” process employed by Dox (1913), combined grinding and extraction of juice by high pressure (Buchner, 1898), and low temperatures (Rowland, 1910), are available, after which further precipitation may be carried out. Halderer (1909, 1910, 1912) investigated the conditions influencing filtration of enzymes through porcelain filters. Two interesting recent methods of following protein hydrolysis are by Krebs (1930) and Gates (1930). The former dissolved the protein in bicarbonate solution in the cup of a Warburg manometer in the presence of 5 per cent. carbon dioxide. As hydrolysis proceeds the carbon dioxide tension changes and may be read off on the manometer. Gates measured the reduction in density of exposed photographic film in a photometer, progressive proteolysis of the gelatin leading to release of silver. Viscometric methods are well adapted to the study of breakdown of gelatin (von Gröer, 1912; Haines, 1933). A nephelometric method of following proteolysis has been developed by Rona and Kleinmann (1928). Foreman and Graham‐Smith (1928) worked out titration methods for following the changes in meat broth during growth of Staphylococcus aureus.
THE EVAPORATION OF WATER FROM INSECTS
Authors: MELLANBY KENNETH
Published: January 2008

This article deals with the way in which climatic conditions and insect metabolism affect the rate at which water is evaporated from insects' bodies.

It appears that practically all the water evaporated from insects is lost from the tracheal system. At high temperatures the body wall of the cockroach becomes permeable to water.

Experimental results may be explained by assuming that when the spiracles are closed, the air in the tracheae is saturated, and in most cases it remains saturated when the spiracles are opened. In some cases, however, particularly in very dry air, the air in the tracheae becomes somewhat dry. The evidence for these suppositions is mainly indirect, but appears reasonably conclusive.

The proportion of dry matter in insects, and the ratio of bound water to free, cannot, of themselves, affect the resistance of insects to desiccation. The best protection against desiccation appears to be an efficient mechanism for closing the spiracles, together with the ability to conserve water in the rectum and pass dry excreta.

Experiments in which the rate of loss of water is measured in air of various humidities show that the rate is more nearly proportional to the saturation deficiency of the air than to any other measure of humidity. As the temperature rises, the rate of loss at one saturation deficiency sometimes increases, because the insect opens its spiracles more frequently.

Experiments to determine the conditions of temperature and humidity which limit survival and breeding of various species support the view that the rate of loss of water is proportional to saturation deficiency. In work of this kind, it is important that results be attributed to the effects of humidity only when humidity alone is the causal factor.

The occurrence of optimum temperatures, at which insects can develop over a wider range of humidity than at higher or lower temperatures, is discussed, and a simple explanation is suggested.

The ways in which the various environmental and internal factors influence the rate of loss of water are discussed, and the law governing the rate of evaporation of water from insects is stated in a revised form, and its implications are defined.
PRODUCTION OF LIFE IN THE SEA
Authors: HARVEY H. W.
Published: January 2008

.This review deals with the production of plants in the sea, which is controlled by a mosaic of factors, many of which are interrelated. Observations are collected and discussed, which relate to (i) the compounds of nitrogen and phosphorus directly utilized by the phytoplankton, and their rate of supply to the photosynthetic zone; (ii) the depth of this zone, which is determined by the quantity of light energy entering the water daily and the transparency of the water; (iii) the influence of temperature, of light, and of the concentration of nutrient salts, upon the growth rate of some diatoms; (iv) the dual effect of turbulence which, on the one hand, carries nutrient salts from below into the photosynthetic zone and, on the other hand, carries plant organisms to depths below the zone and, in some areas, increases the turbidity of the water thereby reducing the depth of the photosynthetic zone; (v) grazing by herbivores which deplete the breeding stock of plants but also excrete nutrient salts directly into the photosynthetic zone; (vi) the regeneration of nutrient salts by bacteria and enzymes; (vii) the supply of iron and other trace elements, of which manganese and divalent sulphur compounds are needed by some species of diatoms,

The supply of such minor constituents is thought to play a considerable role in the distribution of plant life in the southern South Atlantic, where there is a high concentration of nutrient salts in the waters throughout the year and great differences in the density of the flora between different areas.

Estimates of the magnitude of the annual production of plants below a square metre, arrived at by various indirect methods, are compared.

Fluctuations in the annual plant production from year to year in the English Channel, assessed from the quantities of phosphate present in the water during the winter, show a marked correlation with the density of the fauna.

Recent attempts to estimate the standing crop of phytoplankton in terms of food for animals are described, and tentative estimates of the carbon and phosphorus content of the standing crop below a square metre, when at its maximum in several seas, are compared.
CAMBRO‐ORDOVICIAN CEPHALOPODS
Authors: Miller A. K.
Published: January 2008

Volborthella and Salterella of the Lower Cambrian arc probably pteropods, rather than cephalopods. The oldest undoubted cephalopods are two species of Plectronoceras from the Upper Cambrian of eastern Asia; both are small curved brevicones with ellipochoanitic siphuncles. The oldest American cephalopods are from the uppermost Cambrian of the Ozark region, and they are referable to Shelbyoceras, which in general physiognomy resembles Plectronoceras. The nautiloids appear to have reached a climax during the earliest Ordovician times and again near the close of the Lower Ordovician; the second climax is characterized particularly by the appearance of nautilicones. The majority of Cambro‐Ordovician cephalopods are brevicones, but longicones are fairly abundant, and locally (in the Lower Ordovician) nautilicones are not particularly rare. Evolute specimens with closely spaced adoral septa and modified apertures are mature, rather than senile. Many Cambro‐Ordovician cephalopods have orthochoanitic siphuncles, others holochoanitic. In the adapical portions of the siphuncle of certain Early Palaeozoic holochoanites (both brevicones and longicones) there are numerous closely spaced endocones, which are believed to have developed from diaphragms. The siphuncle of one genus of Lower Ordovician orthochoanites contains a central tube of unknown function. In another Lower Ordovician genus the walls of the siphuncular segments are solid‐V‐shaped in longitudinal section. The adapical portions of at least some of the early nautilicones show a siphonal caecum much like that of modern Nautilus, an orthochoanitic siphuncle, a small umbilical perforation, and a nepionic line near the end of the first volution. Both cameral and siphuncular deposits occur in Lower Ordovician nautilicones. Presumably brevicones gave rise to longicones and these in turn to gyroceracones and nautilicones. During the Lower Ordovician, holochoanites developed from ortho‐choanites; and cyrtochoanites, which in America at least are not known to exist before the Middle Ordovician, also evolved from orthochoanites.
THE INVESTIGATION OF PLANT NUTRITION BY ARTIFICIAL CULTURE METHODS
Authors: ARNON D. I. , HOAGLAND D. R.
Published: January 2008

This review presents a general survey of artificial culture methods employed in the investigation of plant nutrition. Several types are described, including liquid‐culture methods and those which depend on a solid inert medium. The advantages of artificial culture procedures for growing plants are pointed out, as one means of studying soil‐plant interrelations, as well as various questions in plant physiology and plant biochemistry. These methods have been indispensable in the study of the chemical elements essential to the growth of higher plants, especially of those elements needed in minute quantities. The techniques of artificial culture are also of great value for the investigation of the absorption of ions by roots. These techniques serve likewise for inquiries into the interreactions of climatic conditions and mineral nutrients. Among other topics considered are the application of artificial culture methods to researches on the functions in plant metabolism of inorganic nutrients, the role of colloids in absorption of ions, horticultural and agronomical problems, and commercial production of crops.
THE STRUCTURE and PERMEABILITY OF BLOOD CAPILLARIES
Authors: DANIELLI J. F. , STOCK A.
Published: January 2008

(1) Outside the single layer of endothelial cells composing the basic unit of the vertebrate blood capillary is a perithelium of connective tissue fibres, associated with which are connective tissue cells, contractile (Rouget) cells, etc. (2) Constriction of the lumen of a capillary may occur (a) by the intrusion of a few endothelial cells into the lumen, (6) by a more general activity of a length of endothelium, or (c) by the action of extra capillary cells, in which case folding of the capillary may ensue. (3) The rate of nitration through the capillary walls is controlled by (a) mechanical factors, (6) plasma and hormone factors, (c) local tonus and nervous control, (d) dietary factors. (4) The conclusion that there is a gradient of permeability to certain dyes is due to a misunderstanding of the experimental observations: the distribution of dye in such cases is precisely that predictable by Starling's ultrafiltration hypothesis for the case of a capillary slightly permeable to colloid. (5) Poiseuille's equation applies fairly accurately to the flow in blood capillaries, and the rate of development of oedema in perfused preparations obeys an equation based on Starling's hypothesis and on Poiseuille's equation. (6) Most substances reach the tissue cells as a result of filtration through the pores in the intracellular cement. Only a few substances, such as oxygen, pass with readiness through the endothelial cells themselves. (7) The capillary network may undergo changes which, with a given systemic blood flow, permit of independent variation (a) in the rate of blood flow through a tissue, (b) in the rate of filtration through the walls of the capillaries.
THE SHOOT APEX IN PTERIDOPHYTES
Authors: WARDLAW C. W.
Published: January 2008

(1) Some of the developments which have made for a fuller understanding of the shoot apex in pteridophytes are discussed, particular attention being paid to morphogenetic processes, (2) Of the several interpretations of growth and cellular arrangement at the apex which have been advanced, that of Naegeli, in which the importance of the apical cell is emphasized, appears to be most applicable to the livingpteridophytes; Sachs's geometrical‐mechanical views emphasize another aspect of organization at the shoot apex, while his comprehensive outlook on the nature of the meristematic region as a whole deserves careful attention. (3) In the pteridophytes, with some exceptions, there is no obligate relation between apical segmentation and organogenesis and histogenesis, i.e., segmentation does not determine organogeny. (4) The value of the facts of apical segmentation in phylogenetic studies is discussed. (5) The history of causal morphology is briefly outlined. If the phyletic history of plants were before us in full, the problems of causal morphology would still remain. These includethe external and internal factors which determine morphogenetic processes and specific structural organization. (6) The development of leaf primordia in ferns and in dicotyledons is compared: the data show that a knowledge of the fern leaf may be regarded as essential to any general theory of leaf development. Such a theory must include a consideration of spatial, metabolic and mechanical factors. (7) The view is developed that shoot buds in ferns occupy an interfoliar position at the time of their inception, the position which they eventually occupy on the shoot or leaf base being determined by the distribution of growth. Bud development thus requires a study of the integrated growth activities at the apex. (8) An account is given of the initial and subsequent differentiation and development of vascular tissue at the shoot apex; spatial, metabolic and mechanical factors which may be implicated are discussed. The view‐is held that the structural arrangements observed should be interpreted in terms of growth and not of adult functional activities. (9) Views based on comparative studies which relate to the fundamental nature of the shoot are of two kinds, i.e. axial and phytonic, a constructional unit being taken for granted‐in each case. It is anticipated that investigations of the growing point from the standpoint'of causality may eventually lead to new concepts regarding the shoot type of organization. An indication is given of some of the factors which may lend themselves to further investigation.
THE ONTOGENY OF THE SHOOT APEX IN DICOTYLEDONS
Authors: PHILIPSON W. R.
Published: January 2008

Work on the early appearance of the shoot apex in the embryo has been carried out along two lines. First, by formal descriptions of early segmentation, and, secondly, by the recognition of zones within the embryo which foreshadow the tissue systems of the seedling. The latter is the more fruitful approach when problems of wide morphological interest are being investigated. A study of this kind has suggested, for example, that the shoot is homologous with the stele of the root, the outer tissues of the root having no counterpart in the shoot.

The tunica‐corpus concept can now be accepted only with considerable reservations. The depth of the tunica may fluctuate during development, and the tissues derived from an apical layer may vary quite capriciously. Nevertheless, stratification of the apex is considered a characteristic feature of angiosperm shoot apices. Complementary to this stratification is a zonation within the apical meristem corresponding to that of gymno‐sperms. That is to say, the central cells of the apical meristem are larger with less dense protoplasm than the surrounding peripheral cells. The term initiating cell is proposed for this stage in cellular development.

The initiation of leaves and the delimitation of provascular meristem below the apex are briefly described, and the bearing of these facts on the relationship between stem and leaf is discussed. The shoot is regarded as a unit, and it is concluded that the angiosperm leaf may be regarded more properly as an outgrowth of the stem than as a modified branch system.

Some recent work on phyllotaxis is discussed, it being shown that an experiment designed to demonstrate that the position of leaf primordia is independent of the pattern of vascular tissue below them is inadequate for this purpose. An interesting theory of phyllotaxis recently propounded by Plantefol fits many facts of apical development.

Little is known of developmental changes during vegetative growth. Those which precede flowering are better known, and seem to be explicable in terms of a redistribution of growth. These changes in the position, rate and direction of cell divisions bring about changes in the organization of the apical meristem in reproductive apices. With the cessation of growth in length, the central zone is replaced by cells of the same nature as those of the peripheral zone, which then extends uniformly over the apex. Gregoire's view of the irreducibility of the reproductive and vegetative apices is examined. Most of his evidence has proved ill‐founded, but a difference in organization remains. This change in organization is regarded as one of a series which occur in the development of the shoot; only with the accomplishment of all stages in its development is a shoot complete.
THE REPTILIAN CEREBRAL HEMISPHERES
Authors: GOLDBY F. , GAMBLE H. J.
Published: January 2008

1. The reptilian hemisphere has been studied mainly from a morphological point of view and for the most part with techniques which are capable of providing no more than a preliminary survey of the distribution of the perikarya of neurones and of the topography of the main fibre systems.

2. The hemisphere is small, and almost completely smooth. Its most characteristic feature is a strio‐amygdaloid complex of great relative size, and in particular the differentiation of the dorsal part of the striatum.

3. Olfactory structures are very well developed in Chelonia which in this respect resemble amphibians and primitive mammals. They are proportionately smaller in other reptilian orders, and some lizards are microsmatic. The pattern of the olfactory connexions resembles that of amphibians and mammals. A characteristic feature of many of the Squamata is a high degree of development of the accessory olfactory bulb and of the amygdaloid nucleus which receives fibres from it.

4. A cortex showing some of the characteristics of the mammalian cerebral cortex is present in all reptiles, and hippocampal, dorsal and piriform areas are always recognizable. The dorsal area occupies a region where the mammalian neocortex must have been formed. A thickening in its anterolateral border (the ‘primordium neopallii’ of some authors) may represent a phylogenetic stage in the development of the mammalian neocortex. Equally valid arguments can be produced for regarding it as a reptilian specialization and for deriving the mammalian condition from the more generalized amphibian condition.

5. Embryological investigations are purely descriptive and have shown little more than that the pattern of development of the reptilian hemisphere conforms in its general features to that of other tetrapod classes.

6. Functional investigations indicate that the basal parts of the hemisphere may be of importance in effecting orientation between the animal and its environment, perhaps by facilitating neural mechanisms at lower levels and by integrating the elements of behaviour patterns. The results so far as the cortex is concerned are mainly negative; nothing comparable to the mammalian ‘motor area’ is present.

7. The limitations of the techniques employed are discussed, and it is concluded that the main value of the information at present available is as a basis for systematic classification, and for application of experimental techniques necessary for the investigation of morphogenetic and functional problems.
MATING SYSTEM AND SEXCUL DIMORPHISM IN LARGE TERRESTRIAL, MAMMALIAN HERBIVORES
Authors: JARMAN PETER
Published: January 2008

Sexual dimorphism in mammals is not entirely satisfactorily explained by the models that are advanced to account for it among birds. This may be because species‐specific styles of being dimorphic, and of attaining mature dimorphic state, are not clearly recognized. Mature dimorphism is a syndrome involving body size, appearance and weaponry; each facet and the whole syndrome may have functions in both fighting and signalling. The mature dimorphic stage has to be reached by growth and change from juvenile and sub‐adult states.

The occurrence of the separate facets of the dimorphic syndrome are reviewed in species of Bovidae, Cervidae and Macropodidae, large, diverse families of eutherian (the first two) and metatherian mammals, which have broadly similar ecological adaptations. In each family the smallest species tend to be homomorphic, with small, inconspicuous weapons. Greatest dimorphism in size is found in medium‐sized bovids and cervids, and the larger macropodids (in which no species exceeds 100 kg male weight); the range of species showing greatest dimorphism in size also shows the most exaggerated weapons. Mature dimorphism is reached by different patterns of growth, which may be determinate and similar in the sexes (leading to homomorphism), determinate but differing between the sexes, or indeterminate and differing, both of which lead to heteromorphism.

The syndromes of dimorphism and patterns of growth are associated and a classification of styles of dimorphism is presented. The adaptiveness of the styles is suggested in terms of what is known of the socio‐ecology, in particular the male reproductive strategies, of the species. The various styles of heteromorphy appear to be associated with males' way of achieving polygyny: such as by non‐resource‐based territoriality, by dominance‐determined access to oestrous females, or by wandering and formation of a consortship with pro‐oestrous females. The relevance of the species' ecology of use of resources to these styles of dimorphism and mate‐acquisition is briefly discussed.
THE EVIDENCE OF REPRODUCTIVE MECHANISMS IN FOSSIL DASYCLADS (ALGAE: CHLOROPHYTA)
Authors: ELLIOTT GRAHAM F.
Published: January 2008

Dasyclads (members of Order Dasycladales: Algae, Chlorophyta) are reviewed for evidence of reproductive structures in the fossil state, and then compared with what is known of the reproductive processes in living examples. The effects of poor preservation in most of the fossils are shown to result in many uncertainties, and the resulting degree of interpretation required is emphasized. Selected genera of fossil dasyclads considered relevant to this problem are briefly analysed and discussed: Archaeobatophora (Ordovician), Kulikia (Carboniferous), Imperiella (Permian), Stichoporella (Jurassic) and Cympolia (Cretaceous to Recent). The pioneer views of J. Pia on dasyclad reproduction through geological time are seen to need much modification in the light of later work. The fundamental dasyclad nucleus‐fragmentation‐reproduction mechanism is believed to have operated within the great morphological variety of known dasyclads, giving rise to modification in genera where basic evolution was structural. In this way the variety of dasyclads can be seen to be the result of varied morphological evolution, often modified by the consistently simple basic reproductive mechanism.
CAPTOPRIL AND BARORECEPTOR REFLEX RESPONSES TO PRESSOR AND DEPRESSOR STIMULI IN THE RABBIT
Authors: PETTY MARGARET A. , REID J. L.
Published: January 2008

The reflex effects of intravenous phenylephrine, sodium nitroprusside or acute haemorrhage in rabbits were examined as indices of baroreceptor reflex function.

The slope of the linear regression of heart period: mean arterial pressure relationship was significantly greater (P<0.01) when buffering the pressor stimulus than either depressor stress.

Captopril (1 mg/kg i.v.) had no effect on the slope of the relationship to either pressor or depressor stimuli.

The clinical and experimental observation of hypotension without bradycardia after captopril could not be confirmed in the present study to be a result of changes in baroreflex sensitivity.
PHARMACOLOGICAL APPROACHES TO THE CHARACTERIZATION OF β‐ADRENORECEPTOR POPULATIONS IN TISSUES
Authors: O'DONNELL STELLA R. , WANSTALL JANET C.
Published: January 2008

The locations of the Schild plots for a selective β‐adrenoreceptor antagonist using different agonists have been used as a means of determining whether the β‐adrenoreceptor population of a tissue is heterogeneous (β1 plus β2) or homogeneous (β1 or β2).

On guinea‐pig trachea, Schild plots for ICI 118,551 (β2‐selective adrenoreceptor antagonist), obtained using fenoterol (β2‐selective) or noradrenaline (β1‐selective) as agonist, were separated, indicating a heterogeneous β‐adrenoreceptor population. In contrast, Schild plots for a non‐selective antagonist, pindolol, using the same two agonists, were superimposed.

On guinea‐pig trachea, the Schild plot for ICI 118,551 with salbutamol (β2‐selective agonist) was superimposed on that with fenoterol (slopes of both plots were close to unity). The Schild plots for ICI 118,551 with adrenaline or rimiterol (β2‐selective agonists) gave pA2 values similar to those obtained with fenoterol or salbutamol as agonist, although the slopes of these plots were less than unity. The Schild plot obtained using any of these β2‐selective agonists was clearly separated from that using noradrenaline. This was in contrast to guinea‐pig atria where Schild plots were superimposed whatever the β‐adrenoreceptor agonist used.

These data confirmed that, in a tissue with a heterogeneous β‐adrenoreceptor population, separated Schild plots for an antagonist are obtained only if the antagonist is selective and if agonists of differing selectivity are used. This is the theoretically predictable result.

Data were also obtained (for the positive chronotropic response of guinea‐pig, rat and cat atria and for the relaxation response of guinea‐pig trachea) using another method for determining whether or not the β‐adrenoreceptor population of a tissue is homogeneous. This method did not require the use of selective agonists.

The concentration ratios obtained for the antagonism of isoprenaline by atenolol (β1‐selective) and ICI 118,551 alone and then in combination, indicated the involvement of a single β‐adrenoreceptor population in responses of guinea‐pig and rat atria but not of cat atria and guinea‐pig trachea. These results were consistent with conclusions from Schild plot experiments that positive chronotropic responses in rat and guinea‐pig atria involve only β1‐adrenoreceptors whereas chronotropic responses in cat atria and relaxation of guinea‐pig trachea involve both β1 and β2‐adrenoreceptors.
THE EFFECTS OF COCAINE AND LIGNOCAINE ON THE RAT RIGHT VENTRICLE IN VITRO
Authors: DOGGRELL SHEILA A. , VINCENT LYNN
Published: January 2008

The effects of cocaine and lignocaine on the contractile responses to field stimulation and to exogenously applied agents, in the absence of other stimuli, have been investigated in the rat right ventricle using methods we have recently described (Doggrell & Vincent, 1981a). In addition the effects of 3H accumulation from (−)‐[3H]‐noradrenaline and on the spontaneous and field stimulation‐induced overflow of 3H, following preloading of the tissue with (−)‐[3H]‐noradrenaline, are reported.

Cocaine, but not lignocaine, inhibited the accumulation of 3H from (−)‐[3H]‐noradrenaline. The spontaneous overflow of 3H, following preloading of the tissue with (−)‐[3H]‐noradrenaline was not altered by cocaine, 10μ, or lignocaine, 100μM. 10μM Lignocaine had no effect on the overflow of 3H evoked by field stimulation at 5Hz. Lignocaine, 100μM, increased and cocaine, 1 and 10μM, reduced the decline in evoked release of 3H. This effect of lignocaine probably represents a decrease in nerve excitability and that of cocaine inhibition of neuronal uptake of noradrenaline.

Cocaine, μM, reduced the rate of beat response to tyramine, 1μM, alone, probably by inhibiting the neuronal uptake process.

Cocaine, 1 and 10μM, had no effect on the contractile responses to field stimulation (at 2 and/or 5Hz). The rate of beat to (−)‐noradrenaline or (−)‐isoprenaline, 1μM, alone was decreased by cocaine, 10μM. Lignocaine, 10μM, reduced the force of contractions to field stimulation at 5 Hz and the responses to (−)‐noradrenaline or (−)‐isoprenaline alone. It is suggested that the inhibitory effects of cocaine and lignocaine on responses to (−)‐isoprenaline in the rat right ventricle are due to a decreased postjunctional membrane excitability. The inability of 10μM cocaine to potentiate contractile responses to endogenous or exogenous (−)‐noradrenaline as a consequence of the inhibition of neuronal uptake is also probably due in part to decreased post‐junctional excitability of the right ventricle.
IMPAIRMENT BY NIFEDIPINE OF VASOPRESSOR RESPONSES TO STIMULATION OF POSTSYNAPTIC α2‐ADRENORECEPTORS IN GANGLION‐BLOCKED RABBITS. FURTHER EVIDENCE FOR THE SELECTIVE INHIBITION OF POSTSYNAPTIC α2‐ADRENORECEPTOR‐INDUCED PRESSOR RESPONSES BY CALCIUM ANTAGONISTS
Authors: VAN MEEL J. C. A. , ZOETEN K. DE , TIMMERMANS P. B. M. W. M. , VAN ZWIETEN P. A.
Published: January 2008

After ganglionic blockade and bilateral vagotomy, vasopressor responses induced by activation of postsynaptic α1‐ and α2‐adrenoreceptors were elicited in the intact circulatory system of rabbits.

The hypertensive effects of the selective stimulating agents methoxamine (α1‐agonist) and B‐HT 920 (α2‐agonist) were effectively antagonized by the adrenoreceptor antagonists prazosin and yohimbine, respectively. These findings confirm the existence of two types of postsynaptic α‐adrenoreceptors (α1‐and α2‐type) in vascular smooth muscle of rabbits.

The calcium antagonistic drug nifedipine did not affect the maximal increase in diastolic pressure brought about by methoxamine, whereas it strongly inhibited the hypertensive effects of B‐HT 920.

It is concluded that this confirmation of the selective inhibition of postjunctional α2‐adrenoreceptor‐mediated vasopressor responses by a calcium antagonistic drug, such as nifedipine, indicates that this activity constitutes a general phenomenon. This finding supports the hypothesis that an influx of extracellular calcium is necessary for the vasoconstriction mediated by postsynaptic α2‐adrenoreceptors.
EFFECTS OF CATECHOLAMINES ON PREGNANT RAT UTERUS
Authors: BOYLE FRANCES C. , DIGGES K. G.
Published: January 2008

The effects of noradrenaline (NA), adrenaline (Adr) and isoprenaline (Iso) have been studied on pregnant rat uterus, at various stages of gestation ‐ on the 10th and 20th days of pregnancy and on the first day post‐partum.

The three catecholamines were inhibitory in all stages of gestation, with the same order of potency as observed in non‐pregnant uteri (ie Iso > Adr > NA). However, mean pD2 values for the catecholamines tended to decrease as gestation progressed.

In 20 day pregnant and 1 day post‐partum uteri, in the presence of propranolol, NA and Adr produced consistent α‐adrenoreceptor mediated motor responses.

It is concluded that in the rat uterus, a form of pregnancy reversal occurs, in that there is a decrease in β‐adrenoreceptor responsiveness, and an increase in α‐adrenoreceptor responsiveness towards the end of gestation, and immediately post‐partum.
THE REGROWTH OF RIGHT ATRIAL NORADRENERGIC NERVES AFTER 6‐HYDROXYDOPAMINE IN GENETICALLY DIABETIC MICE: EFFECTS OF INSULIN TREATMENT
Authors: MAYER J. HEIDI , CLARKE SHARON A. , WILSON HILARY F. , TOMLINSON D. R.
Published: January 2008

1 This study examined the rate of repletion of right atrial noradrenaline levels after a single dose (100 mg/kg i.p.) of 6‐hydroxydopamine (6‐OH Da) in diabetic and non‐diabetic mice of the C57 BL/KS db/db strain.

2 In mice which received no 6‐OH Da there was no significant difference, in endogenous noradrenaline levels, between diabetic and non‐diabetic animals. The depletion of noradrenaline 24 h after 6‐OHDa was slightly more profound in the diabetic mice than in non‐diabetic controls. Thereafter the rate of repletion of noradrenaline was more rapid in the diabetic group.

3 The normal noradrenaline content was reinstated in diabetic mice between 7 and 10 days after 6‐OHDa. In the non‐diabetic group levels similar to those found in untreated mice were not reinstated until 14 days after 6‐OHDa.

4 Ten days after 6‐OHDa right atria from diabetic mice were markedly more responsive to stimulation of the intramural noradrenergic nerves than were preparations from non‐diabetic mice.

5 A group of diabetic mice was treated with insulin (10 m Units/g daily) for 6 weeks. The right atria from these animals, examined 10 days after 6‐OHDa, were similar in their responses to noradrenergic nerve stimulation to the preparations from the non‐diabetic mice.

6 All these groups of atria gave similar responses to exogenous noradrenaline. These findings indicate that regrowth of noradrenergic terminals after 6‐OHDa was more rapid in diabetic mice than in either insulin‐treated diabetic mice or non‐diabetic mice.
ARYLAZIDO AMINOPROPIONYL ATP (ANAPP3) ANTAGONISM OF CAT URINARY BLADDER CONTRACTIONS
Authors: THEOBALD R. J.
Published: January 2008

1 ANAPP3 produces a transient contraction of the urinary bladder of the cat similar to that produced by ATP and hypogastric nerve stimulation.

2 ANAPP3 partially antagonizes the inhibition of pelvic nerve‐evoked bladder contractions induced by adenosine, possibly by blocking P1 receptors.

3 ANAPP3 antagonizes contractions of the cat urinary bladder induced by ATP, β, γ‐methylene ATP, pelvic nerve stimulation and hypogastric nerve stimulation.

4 ANAPP3 produces no antagonism of either noradrenaline‐induced inhibition of pelvic nerve‐evoked bladder contractions or acetylcholine‐induced bladder contractions, thereby substantiating the specificity of the effect of ANAPP3 against purines.
CHOLINERGIC INFLUENCES ON THE SPINAL CARDIOVASCULAR NEURONES
Authors: BHARGAVA K. P. , PANT K. K. , TANGRI K. K.
Published: January 2008

In bilaterally vagotomized and spinal cord (C1) transected dogs, intrathecal (i.t.) injection of pilocarpine decreased while DMPP increased the blood pressure. These responses were antagonized by i.t. pretreatment with ethylbenztropine and chlorisondamine respectively.

No change in the resting heart rate occurred after intrathecal injection of cholinergic drugs in these animals.

The post‐coronary artery ligation cardiac arrhythmia, in bilaterally vagotomized and spinal (C1) transected dogs, was inhibited by i.t. pilocarpine and chlorisondamine and facilitated by ethylbenztropine and DMPP.

The effects of muscarinic and nicotinic receptor agonists on the arrhythmia were blocked by their respective blockers.

It appears that the muscarinic receptors are inhibitory while nicotinic receptors are facilitatory for spinal control of vasomotor tone and the post‐coronary artery ligation cardiac arrhythmia. However, the spinal muscarinic and nicotinic receptors do not appear to have a significant role in the regulation of normal heart rate.
THE CHRONIC EFFECTS OF β‐ADRENORECEPTOR BLOCKING AGENTS ON TRANSMITTER OVERFLOW IN THE ANOCOCCYGEUS MUSCLE OF THE RAT
Authors: CARR SUSAN S. , DRAPER A. J. , LAMAA MICHEL , REDFERN P. H.
Published: January 2008

1 The effect of chronic administration of three β‐adrenoreceptor blocking agents, propranolol, timolol and atenolol on transmitter release from sympathetic nerves has been investigated in the isolated anococcygeus muscle of the rat.

2 Oral treatment for 11 weeks with either propranolol (12 mg/kg/day), or timolol (1.2 mg/kg/day) but not atenolol (12 mg/kg/day) significantly increased the stimulation‐induced overflow of radioactivity following preincubation of the tissue with 3H‐NA.

3 No increase in end‐organ sensitivity, as measured in terms of responsiveness to exogenous acetylcholine, tyramine or NA, was observed.

4 The ineffectiveness of atenolol compared to the other β‐adrenoreceptor blocking drugs may be related to the finding that, in acute experiments, atenolol inhibited tissue uptake of 3H‐NA.

5 It is postulated that increased release of transmitter may be related to prolonged blockade of presynaptic β‐receptors and a resultant increase in presynaptic receptor sensitivity.
DIFFERENCES BETWEEN RECEPTORS FOR 5‐HYDROXYTRYPTAMINE ON AUTONOMIC NEURONES REVEALED BY NOR‐(–)‐COCAINE
Authors: FOZARD J. R.
Published: January 2008

1 The interaction between nor‐(–)‐cocaine and 5‐hydroxytryptamine (5‐HT) at autonomic neuronal 5‐hydroxytryptamine (5‐HT) receptors has been investigated on the rabbit heart and guinea‐pig ileum.

2 The chronotropic response to 5‐HT mediated through activation of receptors on the terminal sympathetic fibres of the rabbit heart was antagonized selectively and surmountably by nor‐(–)‐cocaine. Schild analysis yielded a pA2 value for the interaction of 7.79 ± 0.11, n = 13.

3 On the guinea‐pig ileum induced to contract by activation of 5‐HT receptors on the intramural cholinergic nerves, nor‐(–)‐cocaine was also a selective and surmountable antagonist of 5‐HT, although the concentrations needed were higher than those shown to be effective on the heart. The pA2 value for the interaction was 6.49 ± 0.07, n = 16.

4 The differential blocking effect of nor‐(–)‐cocaine in the two tissues suggests that the receptors for 5‐HT on the cholinergic nerves of the ileum and the sympathetic fibres of the heart are different. The data thus lend support to the earlier similar conclusion based on the observation that 5‐methoxytryptamine is a potent agonist on the ileum yet inactive on the heart.
EFFECTS OF PRAZOSIN, PHENTOLAMINE AND YOHIMBINE ON NORADRENERGIC TRANSMISSION IN THE RAT RIGHT VENTRICLE IN VITRO
Authors: BRADLEY LYNN , DOGGRELL SHEILA A.
Published: January 2008

1 The effects of prazosin, phentolamine and yohimbine on the accumulation of radioactivity from [3H]‐noradrenaline, and on the subsequent spontaneous and field stimulation‐evoked outflow of radioactivity have been investigated in the rat right ventricle in vitro. In addition the effects of these agents on contractions produced by exogenous amines or by field stimulation are reported.

2 Prazosin, phentolamine and yohimbine had no effect on the accumulation of radioactivity from [3H]‐noradrenaline.

3 The decline in the spontaneous outflow of radioactivity, following loading of the tissue with [3H]‐noradrenaline, was reduced by prazosin (1 times 10‐8 or 1 times 10‐7M) and 1 times 10‐6M yohimbine. Phentolamine and 1 times 10‐7M yohimbine had no effect on the spontaneous outflow of radioactivity.

4 Prazosin, phentolamine and yohimbine (all at 1 times 10‐7M) reduced the decline in outflow of radioactivity evoked by field stimulation at 5Hz. In the presence of yohimbine, prazosin or phentolamine had no effect on the evoked outflow. The effect of prazosin, phentolamine and yohimbine alone probably represents antagonism at prejunctional α‐adrenoreceptors.

5 The rate of beating and force of contractions evoked by 1 times 10‐6M isoprenaline were not altered by prazosin, phentolamine or 1 times 10‐7M yohimbine. The rate of beating evoked by noradrenaline (1 times 10‐6M) was reduced by prazosin and phentolamine. Yohimbine (1 times 10‐6M) reduced the rate of beating to isoprenaline and to noradrenaline. These effects of prazosin and phentolamine probably represent antagonism at postjunctional α1‐adrenoreceptors and that of yohimbine a decrease in the excitability of the postjunctional membrane.

6 In the control tissues the force of contractions evoked by field stimulation at 5Hz declined slowly with successive stimulations at 30 min intervals. In the presence of prazosin (1 times 10‐8 and 1 times 10‐7M), phentolamine (1 times 10‐7 and 1 times 10‐6M) and 1 times 10‐7M yohimbine the responses did not decline with successive stimulations. Yohimbine (1 times 10‐6M) had no effect on the stimulation‐evoked responses.

7 Phentolamine or yohimbine (both at 1 times 10‐7M) had no additional effect on the stimulation‐evoked responses in the presence of prazosin (1 times 10‐7M). Prazosin (1 times 10‐8M) and yohimbine (1 times 10‐7M) had no further effect in the presence of phentolamine (1 times 10‐6M). Prazosin or phentolamine (both at 1 times 10‐7M) had no effect on stimulation‐evoked responses in the presence of yohimbine (1 times 10‐7M).

8 In the rat right ventricle, the ability of phentolamine and yohimbine to prevent the decline in the stimulation‐evoked responses with successive stimulations is probably due to antagonism at prejunctional α‐adrenoreceptors. However it is suggested that the ability of prazosin to prevent the decline in response is due to a release of endogenous noradrenaline and to antagonism at prejunctional α‐adrenoreceptors.
INTERACTION OF CLONIDINE, ITS METHYLENE‐BRIDGED ANALOG, St 1913, AND THE BENZYLIC HYDROXYL‐SUBSTITUTED DERIVATIVE, St 1965, WITH α1‐ AND α2‐ADRENORECEPTORS
Authors: RUFFOLO R. R. , TIMMERMANS P. B. M. W. M. , VAN ZWIETEN P. A.
Published: January 2008

The effects of benzylic hydroxyl substitution on the activity of a close structural analog of clonidine was assessed at α1‐ and α2‐adrenoreceptors both in vitro and in vivo in order to uncover possible differences that this substitution may have on the effects of imidazolines and phenethylamines at adrenoreceptors.

In all test systems, the presence of the benzylic hydroxyl group was associated with a consistent and marked decrease in activity. These findings are in agreement with our previous studies with imidazolines having different pharmacological profiles and different physicochemical properties than the clonidine derivatives reported herein.

We conclude, therefore, that the deleterious effects of the benzylic hydroxyl group is ubiquitous among imidazolines and, more importantly, is in marked contrast to the 100–1000 fold enhancement in activity that the benzylic hydroxyl substituent (i.e. β‐hydroxyl group) produces for the phenethylamines.

The results support the concept that imidazolines and phenethylamines may interact differently with α‐adrenoreceptors.
CALCIUM‐DEPENDENCY OF THE PRESSOR RESPONSES TO SELECTIVE 5‐HYDROXYTRYPTAMINE RECEPTOR AGONISTS IN PITHED RATS
Authors: KALKMAN H. O. , BODDEKE H. W. G. M. , TIMMERMANS P. B. M. W. M. , VAN ZWIETEN P. A.
Published: January 2008

The pressor responses to six selective 5‐HT receptor agonists, quipazine, TMFPP, Org 10155, Ru 24969, 5‐methoxytryptamine and 5‐methoxy‐N,N‐dimethyltryptamine, were quantified and tested for calcium dependency following i.v. administration to pithed normotensive rats.

The pressor responses induced by 5‐methoxytryptamine and 5‐methoxy‐N,N‐dimethyltryptamine were not influenced by calcium entry blockade by means of nifedipine.

The piperazine derivatives quipazine, TMFPP and Org 10155 were full agonists, but the pressor responses to these agonists were sensitive to calcium entry blockade.

5‐Methoxy‐N,N‐dimethyltryptamine and Ru 24969 were found to be partial agonists.

It is submitted as a hypothesis that within the present series of 5‐HT receptor agonists, a restricted side chain flexibility will enhance the dependency of their pressor responses to extracellular calcium.