bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Hypovolemic Hypotension on Extra‐ and Intracellular Acid‐Base Parameters and Energy Metabolites in the Rat Brain
Authors: Siesjö B. K. , Zwetnow N. N.
Published: December 2008

Siesjö, B. K. and N. N. Zwetnow. The effect of hypovolemic hypotension on extra‐and intracellular acid‐base parameters and energy metabolites in the rat brain. Acta physiol. scand. 1970. 79. 114–124.

The influence of hypovolemic decreases in the mean arterial pressure upon intra‐ and extracellular acid‐base parameters in the brain, and upon tissue concentrations of ATP, ADP, AMP and phosphocreatine, was studied in immobilized and artificially ventilated rats. Hypotensive periods of 20 or 60 min duration did not lead to any significant changes in ATP, ADP, AMP or phosphocreatine concentrations until the mean arterial pressure was below 40 mm Hg, but there was a small gradual increase in tissue lactate concentration, and in the lactate/pyruvate ratio, even at a moderate decrease in blood pressure. The lactate and pyruvate changes were significant even after corrections for blood and CSF lactate and pyruvate contents, and similar changes were seen in the CSF. The moderate changes in extra‐ and intracellular lactate concentrations did not lead to any noticeable decreases in calculated extra‐ and intracellular pH values since even moderate reductions in blood pressure usually led to small concomitant falls in the tissue CO2 tension. Thus, if it can be assumed that the cerebral blood flow was upheld at the moderately reduced perfusion pressures, the results strongly speak against the possibility that the decrease in cerebrovascular resistance, which occurs during autoregulation of flow in hypovolemic hypotension, is related to extracellular pH changes.
Isolation of 32P‐Labelled Phosphorylserine from Ehrlich Mouse‐Ascites Tumour Cells Suspended in an Isotonic Medium Containing 32P‐Labelled Adenosine Triphosphate
Authors: ÅGren G. , Ronquist G.
Published: December 2008

Ågren, G. and G. Ronquist. Isolation of32P‐labeled phosphorylserine from Ehrlich mouse‐ascites tumour cells suspended in an isotonic medium containing 32P‐labelled adenosine triphosphate. Acta physiol. scand. 1970. 79. 125–128.

Labelled 32P‐phosphorylserine was isolated from Ehrlich mouse‐ascites tomour cells incubated for short periods in an isotonic medium containing γ32P‐ATP. 32P‐orthophosphate could not be incorporated into phosphorylserine under similar conditions unless having been first linked as a terminal phosphoryl group of ATP. Since ATP does not penetrate the cell membrane, it is concluded that the terminal phosphoryl group of ATP has reacted with a protein located at or in the tumour cell membrane.
Some Characteristics of Lipolysis in Dog Adipose Tissue. Effects of Noradrenaline, Prostaglandin E1and Nicotinic Acid
Authors: Carlson Lars A. , Micheli Horace
Published: December 2008

Omental adipose tissue from twelwe fasted dogs of both sexes was incubated in vitro and the glycerol release determined as a measure of lipolysis. The effect of addition of noradrenaline, prostaglandin E1(PGE1) and nicotinic acid into the medium was studied. On basal lipolysis the following effects were obtained with PGE.,0.1 μgPGE Inhibition 4 dogs, no effect 6 dogs. 1 μg PGE1:Inhibition 1 dog, no effect 5 dogs, stimulation 6 dogs,10 pg PGE1: Inhibition 1 dog, no effect 3 dogs, stimulation 8 dogs. A dualistic action of PGE1was seen in some of the dogs. PGE1, 1 μg, inhibited lipolysis stimulated by noradrenaline only in those dogs where the same amount of PGE1either inhibited or did not modify basal lipolysis. In those dogs where 1 μg of PGE1stimulated basal lipolysis, this dose did not inhibit the stimulation caused by noradrenaline. The β‐adrenergic blocker Kö 592 inhibited the stimulation of lipolysis caused by PGE, only slightly while Kö 592 completely inhibited the stimulation elicited by noradrenaline.

Nicotinic acid inhibited the basal lipolysis in five of ten dogs and the stimulation induced by noradrenaline in three of ten. In those dogs where nicotinic acid inhibited lipolysis PGE1was in general also inhibitory.
Parasympathetic Neuro‐Effector Transmission and Functional Vasodilatation in the Submandibular Salivary Gland of Cats
Authors: Gautvik Kaare
Published: December 2008

The present study deals with the effect of different pharmacological agents on the secretory and vasodilator responses caused by stimulation of the chordo‐lingual nerve in cat submandibular salivary glands perfused under conditions of constant volume inflow.

When the gland was perfused with red cellsiuspended in normal cat plasma or in kininogen‐free solutions, the vasodilator and secretory responses raused by stimulation of the chordo‐lingual nerve were mimicked by close arterial injections of acetylcholine. Atropine injected intravenously in doses of 0.5–1 mg/kg did not affect the chorda‐induced vasodilatation while salivary secretion was blocked. Increasing doses of atropine caused a successive reduction in the chorda‐mediated vasodilatation.

Close arterial injections of isoprenaline caused vasodilatation, but no secretion of saliva. Propranolol in doses of 10–200 μg infused into the gland, abolished the effect of injected isoprenaline, but caused a small reduction of the chorda‐mediated vasodilatation. The combined action of propranolol and atropine depressed the long‐lasting vasodilator phase of chorda stimulation while the initial decrease in perfusion pressure was not affected.

The findings suggest that the chordo‐lingual fibres to this gland all are cholinergic and that the nerve‐effector transmissions vary in their atropine sensitivity. The neuroglandular synapse responsible for secretion of watery saliva is easily blocked by atropine. The neuro‐vascular transmission and the neuro‐glandular connection responsible for release of kallikrein, are both relatively atropine‐resistant.
The Mucopolysaccharides in the Myocardium of Growing Rats
Authors: von Knorring Johan
Published: December 2008

No change in the myocardial mucopolysaccharide (MPS) content, measured as uronic acid of alkali‐extracted tissue or hexosamine in papain‐digests of fresh tissue, was observed in rats from the age of 7 days to 18 months. When MPS from papain‐digested myocardial and aortic tissue was separated by electrophoresis on cellulose acetate, three Akian blue‐positive fractions were demonstrated. Identification of the fractions was attempted on the basis of their electrophoretic mobility, their response to testicular hyaluronidase and autoradiography of 35S‐containing fractions. The slowest fraction (fraction 1) was designated hyaluronic acid (HA), fraction 2 was thought to be identical with heparitin sulphate (HS) and fraction 3 with chondroitin sulphate A/C (CS‐A/C). Fractions 1 and 2 in myocardium and aorta had the same electrophoretic properties, while fraction 3 from the two tissues differed in this respect. As calculated from photoscanned strips, HA was predominant in the myocardium and the HS‐like fraction in the aorta. The HA‐peak showed a slight proportional increase in the myocardium with increasing age, corresponding to a decrease in CS‐A/C. The results suggested that the MPS pattern of the myocardium is definitely formed at an early foetal stage and postnatally undergoes only slight age changes.
Concentration of Trypsin Inhibitors of Different Molecular Size and of Albumin and Haptoglobin in Blood and in Lymph of Various Organs in the Dog
Authors: Ganrot P. O. , Laurell C.‐B. , Ohlsson K.
Published: December 2008

The concentration and homogeneity of some plasma proteins in lymph from various tissues in dog was studied immunochemically. Special interest was focused on the enzyme inhibitors, at‐antitrypsin, and α2–macroglobulin. The ratio between the concentrations in lymph and plasma was the same for albumin and α1 antitrypsin, but decreased significantly with increasing molecular size in the order α1–antitrypin, haptoglobin and α2–macroglobulin. The ratio α1–antitrypsin/α2–macroglobulin was, on the average, twice as high in the intercellular fluid as in plasma. The protein content of the lymph varied considerably between the organs with the highest values for lung and liver. These organs also showed the lowest selectivity, expressed as the quotient between the α1–antitrypsin lymph/plasma ratio and the az‐macroglobulin lymph/ plasma ratio. The influence of different rates of lymph flow in different organs on these values is discussed. No enzyme‐inhibitor complexes were demonstrated.
Excitation and Impulse Conduction in the Human Fetal Heart
Authors: Gennser Gerhard , Nilsson Erik
Published: December 2008

Intracellular and bipolar surface electrodes were used to record electrical activity from isolated hearts of human fetuses at midgestation (17–24 weeks). Action potential characteristics for cells in the sinus node, the atrium, the AV‐node, and the ventricle are described. Diastolic depolarizations and subthreshold oscillations indicating latent pacemaker activity were found in arrial cells but not in ventricle cells. Resting membrane potential in ventricle cells was – 81.4 mV at 37°C and an external potassium concentration of 4 mM. With increasing external potassium concentrations, the resting membrane potential increased, within the range 8–64 mM the change was 51.2 mV per tenfold increase in potassium concentration. In 0.5 mM potassium solution, the amplitude of the resting membrane potential declined in ventricle cells and spontaneous action potentials appeared. Within the temperature range 37–19°C, a decrease in temperature increased the resting membrane potential 0.9 mV per°C. Conduction velocity in both atrium and ventricle was 0.4–0.7 mlsec. In ventricle, the conduction velocity decreased with increasing stimulation frequency within the range studied (12–240 stim./min). In atrium, the conduction velocity decreased both at frequencies above 100/min and at very low frequencies. The conduction velocity through the AV‐node was approximately 0.01 m/sec and decreased with increasing stimulation frequency above 100 stim./min.
Relation between Tension and Sensory Response of the Isolated Frog Muscle Spindle during Stretch
Authors: Husmark I. , Ottoson D.
Published: December 2008

The tension developed in the isolated frog muscle spindle during stretch has been studied and related to the impulse response and the isolated receptor potential of the spindle. With a steplike stretch tension rose to an initial peak and then declined towards a steady level. The decay consisted of an initial phase of rapid fall and a later phase of slow decline when stretch was prolonged. The magnitude of the peak and the static level of tension were exponential functions of the amount of stretch. The response of the spindle in terms of the impulse discharge and the isolated receptor potential closely followed the tension changes during various phases of stretch. Adaptation of the spindle to maintained stretch, in terms of the fall of the receptor potential, followed the same general time course as the decay in tension. The results suggest that tension during stretch reflects structural changes within the spindle and that these changes may bear a more direct relation to the sensory response than lengthening. Neither the gross tension nor the elongation ran, however, be regarded as a dirert representation of the actual stimulus to the endings.
Properties of Muscle and Liver Lysosomes in Adrenalectomized Rats
Authors: Berg Trond , Bird John W. C.
Published: December 2008

The stability of lysosomes from liver and muscle of adrenalectomized, young rats has been tested by measuring the release of acid hydrolases (RNase, cathepsin D, β‐glucuronidase and aryl sulphatase) from lysosomes under various conditions. Adrenalectomy increased the proportion of enzyme released from the lysosomal particles, as measured in tissue homogenates or fractions. The release, which may have occurred in vivo or during homogenization, probably reflects an increased lysosomal fragility. In muscle (but not in liver) an increase in the total activtiy of acid hydrolases could also be observed after adrenalectomy. The effects of adrenalectomy could not be corrected by saline treatment, and were not due to reduced food intake. All parameters were restored to normal by administration of 300 μg of corticosterone daily for 5 days, and higher doses (3 mg per day) led to further reduction in enzyme release. The stability of muscle and liver lysosomes in vitro was tested by exposing particles to osmotic stress, vitamin A alcohol and acid medium (pH 5). Liver and muscle lysosomes from adrenalectomized rats were less stable when exposed to osmotic stress or vitamin A, but hepatic lysosome were more stable towards acid incubation than particles prepared from normal rats. Differential centrifugation of liver homogenates indicated that more acid hydrolases were associated with the heavier fractions in homogenates from operated animals. An increased particle size in tissues from the adrenalectomized animals may possibly account for the observed changes in lysosomal stability.
Structurally Based Increase of Flow Resistance in Spontaneously Hypertensive Rats
Authors: Folkow Björn , Hallbäck Margareta , Lundgren Yen , Weiss Lilian
Published: December 2008

The resistance to flow in the maximally dilated systemic vascular bed (except the coronaries) was compared in spontaneously hypertensive rats (SHR) and normotensive controls. – The aortic root was cannulated for perfusion with an oxygenated plasma substitute, both the aortic inflow and the venous effluent via the right heart being recorded continuously. Temperature and viscosity of the perfusate were kept constant and it was checked with supramaximal doses of vasodilator drugs that complete vascular relaxation was at hand. Pressure‐flow curves were plotted and flow resistances at equal pressure heads and transmural pressures were compared. — Flow resistance in the maximally dilated systemic vessels was increased in the spontaneously hypertensive rats to an extent that largely equalled their raised blood pressure during “resting” conditions, the difference to the control animals being highly significant. – The results suggest the presence of a morphological adaptation of the resistance vessels of the entire systemic circuit which raises the structurally set “baseline” for functional vascular adjustments, and which therefore may largely account for the increased flow resistance during rest. These findings are in agreement with earlier studies concerning the regional flow resistance in hypertensive man (Folkow 1956, Sivertsson and Olander 1968).
Bretylium and the Degeneration Contraction of the Sympathetically Innervated Periorbital Smooth Muscle in the Rat
Authors: Lundberg Dag
Published: December 2008

The ability of bretylium to delay the start of the degeneration contraction of the sympathetically innervated periorbital muscle has been studied in conscious rats. The sympathomimetic and neuron blocking action of bretylium at the doses most frequently used were also tested. A low dose, 0.5 mg/kg, that induced no measurable neuron block still delayed. The delay caused by local injection into the muscle exceeded the duiation of the neuron block. These findings indicate that the bretylium‐induced delay is not caused by neuron block and that the delaying action mainly is exerted on the terminal parts of the neurons. Bretylium given repeatedly postponed the onset of the degeneration contraction at least 6 to 10 hrs. Later the processes responsible for the degeneration contraction appeared to develope despite the treatment. Within 4 hrs preceding or just including the start of the degeneration contraction the time of injection was very critical for the effect of bretylium on the time course of the contraction. An injection of bretylium during an ongoing degeneration contraction interrupted the contraction and displaced the latter part for several hrs. Before the interruption the drug seemed to enhance the transmitter release. It appeared that early during the degeneration contraction there are nerve endings at different stages of degeneration on which bretylium acts differently.
Morphogenesis of Myoneural Junctions Induced Postnatally in the Tibialis Anterior Muscle of the Rat
Authors: Juntunen Juhani , Terävänen Heikki
Published: December 2008

The structure of myoneural junctions induced during nerve regeneration outside the zone of previously existing, degenerating myoneural junctions was studied with the light microscope after histochemical demonstration of acetylcholinesterase (AChE) activity in the tibialis anterior muscle of the postnatal rat. The escape of regenerating nerves from their original glial sheaths was produced by severe crushing of the sciatic nerve at different stages of development of the rat, from newborn animals to adults. New myoneural junctions were induced in the previously undifferentiated part of the muscle plasma membrane in animals of all age groups, although not in every individual animal, if the old myoneural junctions did not regenerate. New myoneural junctions were observed in about 70 % of the rats operated on before the age of 10 days and in less than 20 % in the older groups. The older the animal, the fewer new myoneural junctions were seen among the re‐innervated old ones, and in the adult animals a new myoneural junction was only sporadically found

Myoneural junctions were first seen outside the zone of previously existing junctions 14–16 days after the operation. Irrespective of the age of the animal at operation, the postnatally induced myoneural junction was plate‐like in structure during the early stages of morphogenesis. Postsynaptic infoldings appeared between the 16th and 25th days after the operation, the infoldings had become deeper between the 25th and 35th days, and the ramification of the AChE distribution typical of the mature myoneural junctions was observed between the 35th and 45th postoperative days.
Temperature Regulation during Exercise Dehydration in Man
Authors: Ekblom Björn , Greenleaf Carol J. , Greenleaf John E. , Hermansen Lars
Published: December 2008

The effects of mild exercise dehydration (1 % of the body weight) on temperature regulation were investigated in 3 men during continuous and intermittent exercise of 1 hr duration on a Krogh bicycle ergometer with the same average heat production at a relative O2 uptake of 62 % in the environment‐independent zone (22° C Ta and 38 % rh). In both hydration and dehydration, during intermittent work, equilibrium levels of rectal temperature (Tre) were 0.3° C higher than during continuous work. Progressive dehydration elevated equilibrium levels of Tre and mean body temperatures 0.3 to 0.4° C above hydration control values while mean skin temperatures (Ts) were essentially constant at 30±0.2° C. The elevation of Tre with dehydration was due, predominantly, to reduced sweating. It is suggested the sweat depression was due to reduced stimuli from the central nervous system to the glands. These results emphasize the sensitivity of the thermoregulatory system to dehydration and point up the need to control water intake during such experiments.
Uptake of 5‐Hydroxytryptamine by Rat Peritoneal Mast Cells in vitro
Authors: Jansson S.‐E.
Published: December 2008

The mechanism of 5‐hydroxytryptamine (5‐HT) uptake by rat peritoneal mast cells in vitro was studied under different incubation conditions. The uptake reached a saturation level even at low concentration of exogenous 5‐HT resulting in a concentration ratio of more than one thousand times. The uptake during the first hour was more rapid when compared with the slow uptake during succeeding hours. The uptake was dependent on temperature and calcium and magnesium ions. Addition of glucose to the medium did not accelerate the uptake which also was unaffected by pH alteration from 6.0 to 7.4. The proposed active uptake mechanism Tor 5‐HT was supported by the results obtained with metabolic inhibitors; those belonging to the group of uncouplers of oxidative phosphorylation effectively inhibited the uptake while sodium cyanide and sodium azide were without significant effect. Results obtained further indicated that 5‐HT at high exogenous concentrations may passively diffuse into the mast cells.
Estimation of Ionic Concentrations and Intracellular pH in Slices from Different Areas of Rat Brain
Authors: Hertz L. , Schousboe A. , Weiss George B.
Published: December 2008

Tissue spaces occupied by14C‐sucrose and3H‐inulin were measured at different incubation time intervals (15–120 min) in rat brain slices prepared from cortex, cerebellum, caudate, diencephalon and midbrain. Total water content, total Na+and K contents and14C‐DMO (5,5‐dimethyl‐2,4‐oxaolidinedione) spaces were obtained from the same tissues. At all time intervals,14C‐sucrose spaces were larger than corresponding3H‐inulin spaces. After 60 min incubation, the mean values for14C‐sucrose spaces in preparations from different brain areas ranged from 31.5 to 38.1 m1/100 g, whereas the3H‐inulin space mean values were 19.3–26.1 m1/100 g. Average intracellular pH was calculated from14C‐DMO spares in the presence and absence of 3.67 mM procaine. The pH1values obtained using inulin‐derived extracellular spares were 6.91–6.99, and those calculated from sucrose spaces were 6.77–6.89. The contents of K+and Na+showed no distinct regional differences, but a potassium uptake with time could only be observed in preparations from cerebral and cerebellar cortex.
Incorporation and Disappearance of Sulfate in Different Regions of Mouse and Rat Costal Cartilage in vivo and in vitro
Authors: Herbai Georg
Published: December 2008

A rapid and simple method for liquid scintillation counting of 33S‐sulfate in biological tissues is described. Sulfate incorporation per mg dry weight into selected lateral, medial and intermediate regions of ribs was studied using costal cartilage from rats and mice. In vitro, cartilage pieces embracing the osteochondral junction had 2–4 times larger incorporation rate than the remaining homogeneous parts of the ribs, both if entire rib cages or stripped and diced cartilage were incubated. After in vivo injection to rats and mice the incorporation rates of sulfate into the region of the osteochondral junction was 2.6 times that found in “resting” cartilage in rats and 4.4 times in mice. The 35S‐sulfate uptake in the ribs per mg dry cartilage diminished in the caudal direction. Growth of the chest cage was mainly a longitudinal growth of the bony segments. Marked differences in the disappearance rates of previously incorporated sulfate were found in different regions along the rib. Rapid sulfate disappearance was found in the bony segment which, however, had incorporated only one seventh of the amount per mg taken up by “resting” cartilage. The “resting” cartilage segments exhibited a steady slow disappearance rate for sulfate and the osteochondral junction region consisting of several differently active tissues showed a rapid sulfate disappearance in the beginning followed by a slow clearance after 2 weeks similar to that of “resting” cartilage. The necessity of careful selection of costal cartilage samples with respect to regional differences is emphasized.
Dilatation of a Medium‐Sized Artery Immediately after Local Changes of Blood Pressure and Flow as Measured by Ultrasonic Technique
Authors: Ingebrigtsen R. , Leraand S.
Published: December 2008

The effect of changes in blood pressure and flow on the calibre of the medium‐sized artery has been studied in model experiments with an a‐v fistula on the femoral vessels in dogs, On opening of the fistula a large local fall of blood pressure proximal to the fistula and an increase in flow up to 1000 % has been found. With the use of an ultrasonic technique for measurement of arterial diameter—by which it was possible to measure changes in the diameter in the order of 0.001 mm—we found an immediate increase, in the order of 10 %, in the diameter of the femoral artery on the opening of the a‐v fistula. This increase remained as long as the fistula was patent. The results were identical in 5 dogs.

The effect on the diameter of clamping the artery for some time, with consequent removal of the clamp, was examined in 5 dogs. Removal of the clamp itself resulted in only a small and temporary increase in the diameter of the artery. It is concluded that the dilatation of the artery on opening of the fistula must be connected to the sudden increase in flow.
Effects of Secretin on Fat Mobilizing Lipolysis and Cyclic AMP Levels in Rat Adipose Tissue
Authors: Butcher R. W. , Carlson L. A.
Published: December 2008

Secretin, 0.0025 μg/ml, stimulated fat mobilizing lipolysis in rat adipose tissue in vitro, while cholecystokinin was without effect. Various fragments of the secretin peptide (amino acids 1–14, 15–27, 1–23 and 1–6) were inactive in roughly equirnol amounts. Secretin raised the concentration of cyclic AMP in isolated fat cells with a half maximal concentration of 2 × 10‐8M. Secretin also increased the formation of cyclic AMP from ATP in homogenates of isolated fat cells. Nicotinic acid and PGE1 inhibited the effects of secretin in rat fat with regard to lipolytic rate and accuniulation of cyclic AMP.
Releasing Effect of Calcium and Phosphate on Catechol‐amines, ATP, and Protein from Chromaffin Cell Granules
Authors: Lishajko F.
Published: December 2008

Addition of Ca2+3 mM to isolated bovine adrenal niedullary granules incubated in 130 mM K‐phosphate buffer pH 6.8–7.2 causes a rapid initial release of noradrenaline (NA), adrenaline (A), ATP and soluble protein. The effect is increased by addition of 1–6 mg/ml of RNA and inhibited by 1–6 mM Mg2+. The effect of Ca2+is dependent on the presence of phosphate ions in the incubation medium and does not occur in sucrose, RCI or NaCl. Addition of freshly precipitated calcium phosphate is also effective in inducing release, but addition of CaHPO4 or Ca2P2O7 had no effect. CaCl2 0.3–1 mM did not increase the release but was effective together with 1–6 mg/ml of RNA. In the absence of phosphate ions Ca2+and Mg2+as well as the divalent ions Ba2+and Sr2+inhibited the release. The catecholamine releasing effect of Ca2+in the presence of phosphate is reduced by 2 mM ATP and almost completely prevented by ATP‐Mg2+. It is suggested that the increased outflow of granular contents is due to membrane alterations induced by Ca‐phosphate.
The Incorporation of Cholesterol into the Nervous System of the Newly Hatched Chick
Authors: Svanberg Olof
Published: December 2008

The deposition of cholesterol in the myelin of the central nervous system has been compared with that in the myelin of the peripheral nervous system. C14‐4‐cholesterol was injected into the yolk sacs of newly hatched chicks and whole body autoradiography was performed according to Ullberg (1954, 1958). No radioactivity was found in the central nervous system, except in the pineal gland, during the 9 days of the investigation. However, the peripheral nerves were heavily marked. The results indicate the existence of a “blood‐brain barrier” which excludes cholesterol. Most of the cholesterol of the myelin in the brain and the spinal cord is accordingly synthesized in situ, while in peripheral nerves it is derived from the blood.
Plasma Skimming in the Intestinal Tract
Authors: Jodal Mats , Lundgren Ove
Published: December 2008

The “tissue hematocrit” of the different wall layers of the small and large bowel of the cat was studied in three different experimental conditions, i.e. during “resting” blood flow of the denervated intestine, during vasodilatation induced by isopropylnoradrenaline and during nervous vasoconstriction. The “tissue hematocrit” was estimated from the distribution of 51Cr‐labelled red cells and 125I‐labelled human serum albumin. It was demonstrated that the “tissue hematocrit” of the mucosa of the small intestine only amounted to 50–60 per cent of the arterial hematocrit while the “muscularis hematocrit” was 90 per cent of the arterial. Similar results were obtained in the three different experimental situations. The low mucosal “tissue hematocrit” could neither be explained by an extravascular accumulation of 125I‐labelled albumin nor by different degrees of axial streaming of erythrocytes in the different wall layers. The observations are therefore taken to indicate the presence of a plasma skimming in the small intestine of the cat. In the colon the “tissue hematocrit” of the mucosa was only slightly lower than that of the submucosa, the muscularis or the arterial blood indicating that no or only a slight plasma skimming occurs in this organ.
Blood Flow through Limb Muscles during Heavy Rhythmic Exercise
Authors: Folkow B. , Gaskell P. , Waaler B. A.
Published: December 2008

The effect of rhythmically performed muscle contractions on blood flow through muscles was investigated in the calf of cat. During a series of contractions, which had led to maximal dilatation of the resistance vessels, a considerable lowering of the pressure in a small vein from the contracting muscles could be demonstrated between contractions, despite the huge inflow. An optimal effect was obtained when the muscle nerve was stimulated with a short (200–300 msec) impulse train once per sec, a pattern mimicking that during running. Rhythmic contractions of this type led to a characteristic blood flow pattern through the muscles. Arterial inflow to the muscle vascular bed occurred only in between contractions, whereas nearly all the venous outflow from the muscles occurred during the contractions.

The venous pressure reduction occurring between contractions implies a gain in effective perfusion pressure and a corresponding augmentation in blood flow through the muscles. Such an effect was found to be considerable in dependent limbs. Here average blood flow through the rhythmically contracting calf muscles could be as great as, or even greater than, the “free” flow in the immediate post‐exercise period. This effect of the “muscle pump” may be of great importance also in the dependent limbs of man.
Distribution of Choline Acetyltransferase in the Hearts of Mammals
Authors: Ekström Jörgen
Published: December 2008

Choline acetyltransferase activity was estimated in hearts of dogs, cats, rabbits and rats. The ventricles, which form about 90 per cent of the fresh weight of the hearts, are responsible for about two thirds of the total enzyme activity of the heart in dogs, cats and rats, and in rabbits for about half the total activity of the heart. The concentration of the enzyme is higher in the atria than in the ventricles. In dogs the apex of the ventricles showed the same enzyme concentration as the basal parts; in cats and rabbits it was somewhat lower in the apex than in the base. The findings are discussed in relation to the controversial question of a parasympathetic innervation of the mammalian heart ventricles.
Background of Increased Flow Resistance and Vascular Reactivity in Spontaneously Hypertensive Rats
Authors: Folkow Björn , Hallbäck Margareta , Lundgren Yen , Weiss Lilian
Published: December 2008

The hindquarters of a spontaneously hypertensive rat (SHR) and a matched normotensive control rat (NCR) were perfused at a constant rate of flow with oxygenated plasma substitute in 15 paired experiments. As is the case in the entire systemic vascular bed (Folkowet al.1969), flow resistance was raised even during maximal dilatation in SHR (p<0.001), almost in proportion to their raised blood pressure. Graded noradrenaline (NA) infusions showed identical NA “thresholds”, while SHR displayed a steeper curve, relating log NA dose to resistance response (p<0.001) and a greater maximal contractile strength of the resistance vessels (p<0.001). These characteristics of the resistance curves for SHR and NCR were compared with those mathematically deduced for two hypothetical vessels, identical except for the presence in one of them of a 30 per cent increase of its media thickness encroaching upon its lumen even at complete relaxation. In all essential points the relationships between the two sets of curves were the same while no other type of vascular change, structural or functional, could alone reproduce all the characteristics of the SHR curve. The results therefore suggest the presence of an increased contractile wall mass in the systemic resistance vessels of SHR encroaching upon their lumina even during maximal dilatation. Without necessitating any increased smooth muscle activity the haemodynamic effects of the proposed structural change can largely alone account for the raised resistance and increased vascular “reactivity” in SHR.
Potentiation by Various Smooth Muscle Stimulants of an Isolated Sympathetic Nerve‐Seminal Vesicle Preparation from the Guinea‐Pig1
Authors: Sjöstrand Nils O. , Swedin Göran
Published: December 2008

The contractions of the seminal vesicle in response to hypogastric nerve stimulation or coaxial stimulation were recorded with a balloon inserted in the lumen of the seminal vesicle.

Adrenaline (A), noradrenaline (NA), acetylcholine (Ach), histamine (Hi), serotonin (5‐HT), barium chloride and high concentrations of angiotensin were found to potentiate the motor response of the seminal vesicle to sympathetic nerve stimulation. This potentiation occurred with concentrations 10–100 times smaller than those giving a direct contraction of the organ. Prostaglandins (PGE1, PGE2 and PGF2a) in low concentrations (1–10 ng/ml) exerted no effect or caused a slight decrease in the response to sympathetic nerve stimulation, while higher concentrations (100 ng–1 μg/ml) enhanced the response to nerve stimulation. This effect was pronounced with PGE1, but rather weak with the other prostaglandins. Oxytocin, vasopressin and felypressin were without effect on the seminal vesicle preparation. It is concluded that the seminal vesicle responds to smooth muscle stimulants in a similar way as the vas deferens.
Single Unit Analysis of Mechanoreceptor Activity from the Human Glabrous Skin
Authors: Knibestöl M. , Vallbo Å. B.
Published: December 2008

Single unit impulses were recorded from the median and the ulnar nerves in waking human subjects with percutaneously inserted tungsten electrodes. 61 mechanoreceptor units in the glabrous skin were analysed with regard to the characteristics of their receptive fields and the basic physiological properties of their endings. 4 different types of receptors could be distinguished. This distinction was based mainly upon the adaptation and the receptive field characteristics although other differences were also observed. The fields had very sharp borders for the majority of the slowly as well as the rapidly adapting units. The field sizes varied considerably: between 10 mm2 and 600 mm2. For a minority of the receptors, slowly as well as rapidly adapting ones, the receptive fields were constituted of a center of high sensitivity and a wide surrounding area of lower sensitivity without distinct borders. The four types of receptors encountered in the present study have striking similarities with four different types of mechano‐receptors which have been described in sub‐human primates, namely the type I and type II slowly adapting, intradermal receptor, according to Iggo's terminology, an intradermal rapidly adapting receptor and the Pacinian corpuscle which is located in the subcutaneous tissues. Roughly 75% of the units were slowly adapting. This is a much larger proportion than found in the monkey. Further, it was shown how the recording method offers the opportunity to analyse the perceptive responses as well as the neurophysiological responses in first order neurons to mechanical stimuli.
The Circadian Fluctuations of the Amount of Free Phosphate and of the Activity of Acid Phosphatase in the Kidneys of Mice and the Effect of UV Radiation upon this Rhythm
Authors: Lindahl Per Eric , Surowiak Jósef
Published: December 2008

The activity of acid phosphatase and the content of Pi1 were estimated in kidney homogenates from male and female mice. The determinations were repeated at 6‐hr intervals during the day, starting at noon, using control animals and animals previously subjected to a high dose of UV radiation. Marked changes in the activity of this enzyme were found during the course of the day, indicating the existence of a circadian rhythm. This phenomenon is observed both in males and in females and exhibits similar features in both sexes. The content of Pi in the kidney homogenate varies in an analogous manner. UV irradiation produced significant changes both in the enzyme activity and in the content of inorganic phosphate. In irradiated animals the new maxima in the activity of acid phosphatase were generally accompanied by maxima in the amount of Pi. It is supposed that the end products of the reactions in the skin formed under the influence of UV radiation and associated with the degradation of phospholipids are the main factors responsible for the observed changes in the kidney.
Effect of Prostaglandin E1on Fat Mobilizing Lipolysis in Rat Adipose Tissue in Relation to the Nutritional Condition
Authors: Carlson Lars A. , Micheli Horace
Published: December 2008

The effect of prostaglandin E1(PGE1) on fat mobilizing lipolysis in rat adipose tissue was studied in relation to the nutritional condition by following the release of glycerol during incubation in vitro. In fed tissues PGE1at concentration of 0.01, 0.1, 1 and 10 μg/ml incubation medium significantly lowered the lipolysis to 64, 41, 48 and 68% of the basal rate (average of 6 expts.). The lipolytic rate was significantly higher with 10 than with 0.1 μg/ml of PGE1. The corresponding figures in adipose tissue from fasted rats were 90, 91, 86 and 95% respectively (average of 7 expts.). These average decreases were not statistically significant. Refeeding fasted rats with glucose one hour before the study restored the sensitivity of adipose tissue to the antilipolytic effect of PGE1. In rat fat the nutritional condition is thus of importance for the appearance of the antilipolytic effect of PGE1. The possible role of the tissue sensitivity to PGE1in regulating fat mobilizing lipolysis during fasting was discussed.
Effects of Some Adrenergic Neuron Blockers, Related Quaternary Ammonium Compounds and Guanidine Derivatives on Degenerating Adrenergic Nerves in the Conscious Rat
Authors: Lundberg Dag
Published: December 2008

Adrenergic neuron blockers, related quarternary ammonium compounds and guanidine derivatives, and some other drugs have been tested on a degenerating nerve‐effector system in the rat periorbital smooth muscle. The main attention was paid to their influence on the degeneration contraction. The quaternary ammonium compounds structurally related to bretylium and xylocholine, with few exceptions, distinctly delayed the onset of the degeneration contraction. The guanidine derivatives known to be related to bretylium and xylocholine pharmacologically caused almost no delay. The simple compound phenyltrimethylammonium (PTMA) was chosen for further studies. It was found to possess actions on the degenerating system similar to those of bretylium. The PTMA‐induced delay was efficiently reduced by desmethylimipramine, but not at all by anticholinergic drugs.

Conclusions: — Guanidine derivatives are much less efficient delayers than related quaternary ammonium compounds. The main structural features essential for delaying activity are found in PTMA. There does not seem to be any correlation between the neuron‐blocking or the sympathomimetic activity and the delaying effect of the drugs. The processes responsible for the onset of the normal degeneration contraction and those effecting the drug‐induced delay do not appear to involve any cholinergic sites.
The Effect of Periarterial Nerve Stimulation on the Jejunal and Ileal Motility in Cat
Authors: Kewenter J. , Pahlin P.‐E. , Storm B.
Published: December 2008

The effect of nervous stimulation of the periarterial nerve trunks along the superior mesenteric artery on the jejunal and ileal motility was investigated. With the same physiological frequencies it was possible to induce excitatory as well as inhibitory motor responses by changing the voltage and/or pulse duration. Guanethidine abolished the inhibitory responses in the jejunum and the ileum. It was concluded that the periarterial nerves contain two different sets of nerve fibres mediating excitatory and inhibitory impulses to the small intestine.
Correlation between the Rise Time of Miniature End‐Plate Potential and the Distance of the Recording Microelectrode from the Myoneural Junction
Authors: Nickels J.
Published: December 2008

A new marking method which permits accurate positioning of the microelectrode tip in the muscle cell and subsequent histochemical staining of the myoneural junction was used to study the correlation between the rise time of miniature end‐plate potentials and the distance of the recording microelectrode from the myoneural junction. The muscle examined was the m.tibialis anterior of the rat. The recording was performed in vivo. A positive correlation was established between the distance and the rise time and the correlation coefficient was +0.94. The mean rise time of the miniature end‐plate potentials in different muscle cells ranged from 0.27 to 0.70 msec., while the distance of the recording microelectrode varied between 0 and 552 μ measured from the midpoint of the motor end‐plate. The rise time was distinctly shorter than is usually reported in the literature.
The Role of Vagal Cardiac Nerves and Arterial Baroreceptors in the Circulatory Adjustments to Hemorrhage in the Cat
Authors: ÖBerg B. , White S.
Published: December 2008

The relative importance of arterial baroreceptors and receptors with afferent fibres in the cardiac nerves, respectively, in producing compensatory circulatory adjustments in moderate hemorrhage was analyzed in chloralose‐anesthetized cats. — The effects of standardized hemorrhage on blood pressure, heart rate and renal and skeletal muscle blood flows were observed before and after section of respective receptor afferents. Both groups of receptors, when operating in the absence of the other, were capable of producing tachycardia and vasoconstriction during a blood loss, but the pattern of response, elicited via the two sets of afferents, differed. Compensation via cardiac nerve afferents thus implied a particularly strong engagement of vasomotor neurons, controlling the heart and the renal vessels, while the arterial baroreceptor adjustments seemed to involve a more uniform exitation of all vasomotor centre neurons. Very rapid hemorrhages often produced a pronounced bradycardia, resembling that seen in the “vaso‐vagal” syncope in man. This response was found to be mediated through a vago‐vagal reflex arch, and probably constitutes a protective mechanism, causing a break on the heart in situations of extremely poor diastolic filling.
The Response of RNA Synthesis to Mitotic Regulation in the Erythron
Authors: Kivilaakso E.
Published: December 2008

Mitotic homeostasis in the erythron appears to be controlled by a humoral feedback mechanism consisting of a tissue‐specific mitotic inhibitor, the erythrocytic chalone, and a tissue‐specific mitotic stimulator. The present report is an account of the way in which these two regulatory factors affect RNA synthesis in normal rat bone marrow cells in vitro. The responses were measured in terms of 3H‐uridine incorporation into the target cells. The primary action of the erythrocytic chalone on 3H‐uridine incorporation was manifested as a rapid and strong inhibition. The initial inhibition was reversible and was followed, after a few hours' incubation, by an increased rate of 3H‐uridine incorporation, which ultimately led to complete compensation of the inhibition. The tissue specificity of these findings was demonstrated indirectly by means of polycythemic target bone marrow, on which the erythrocytic chalone had only a negligible effect. The effect of the mitotic stimulator on 3H‐uridine incorporation in the cells was invariably a stimulation, which showed a slight tendency to increase with incubation time. The results demonstrate that the effects of the mitotic regulatory factors are not restricted to DNA metabolism alone but can also be elicited within other metabolic processes in the cell.
Reduction in Pulmonary Blood Volume after a Blood Loss
Authors: Aarseth Petter
Published: December 2008

There is little information about the possible role of the pulmonary vascular bed as a variable blood depot. An evaluation of the degree of blood mobilization from this vascular compartment after a blood loss has therefore been attempted. Rats were given labelled erythrocytes and albumin, and immediately after a standardized blood loss the circulation was arrested by immersing the animals in liquid nitrogen. The lungs and tissue samples from liver and skeletal muscles were removed, and their blood contents evaluated. Values found in the tissues of the bled animals were compared with those from a group of non‐bled control animals. In a group of animals bled 12% of their total blood volume the mean pulmonary blood volume was reduced by 25%, while the muscle and liver blood contents were reduced by about 10% only. This difference was even more pronounced in a group of animals bled 24% of their total blood volume. The reduction in pulmonary blood volume was in the former group equal to 27% of the lost blood. This was more than the amount of blood contributed from the whole mass of skeletal muscle. In the bled animals the weight of the lung tissue proper was considerably reduced, indicating that there had been a reduction also in lung tissue water.
A Double Isotope Method for Determination of the Miscible Inorganic Sulfate Pool of the Mouse Applied to in vivo Studies of Sulfate Incorporation into Costal Cartilage
Authors: Herbai Georg
Published: December 2008

In vivo sulfate incorporation into tissues of small animals, as a metabolic research tool, has been previously handicapped since convenient micromethods for sulfate determination were lacking. A double isotope method for determination of the inorganic sulfate pool applicable to very small animals is presented and evaluated. It is based on a principle which makes blood samples unnecessary. Phenol injected i.v. is converted to phenyl sulfate in the viscera and the circulating inorganic sulfate pool of the animal participates in this reaction. 3H‐phenol and 35S‐sulfate mixed with suitable amounts of carrier are given to the animals and the tagged phenyl sulfate formed is isolated from the urine by thin‐layer radio‐chromatography. Its 3H/35S ratio together with the specific activities of the injection mixture yield all necessary values for calculation of the size of the sulfate pool. Simultaneously the incorporated amount of sulfate into a defined portion of costal cartilage is measured after correction for the individual sulfate pool values.

In 20 g N.M.R.I. mice the total miscible sulfate pools were about 300–400 μg SO4/mouse and the sulfate incorporation during the 30 min experimental period reached 200–400 nanogram SO4 per 5 pairs of cartilaginous ribs including their osteochondral junctions. The size of the sulfate pool increased with increasing body wegiht at different ages both in N.M.R.I. and in obese‐hyperglycemic mice. The sulfate incorporation rates showed markedly different values in different mouse strains investigated at similar ages.