bluuebunny/crossref_metadata_2025_split huggingface dataset:
Presence of caerulein in extracts of the skin of Leptodactylus pentadactylus labyrinthicus and of Xenopus laevis
Authors: ANASTASI A. , BERTACCINI G. , CEI J. M. , DE CARO G. , ERSPAMER V. , IMPICCIATORE M. , ROSEGHINI M. 
Published: July 2012

The South American amphibian Leptodactylus pentadactylus labyrinthicus and the South African amphibian Xenopus laevis contain in their skin a polypeptide indistinguishable from caerulein prepared from the Australian amphibian Hyla caerulea.
The caerulein content of different batches of Leptodactylus pentadactylus labyrinthicus skins varies from 10 to 500–600 μg/g tissue. Drying of the skin causes either a moderate decrease or a slight increase in the caerulein content. Methanol extraction gives considerably higher yields of caerulein than acetone extraction.
Caerulein or caerulein‐like polypeptides also occur in the skin of several other species of Leptodactylus together with 5‐hydroxyindole alkylamines and imidazole alkylamines. Yet other species of Leptodactylus lack caerulein‐like polypeptides and 5‐hydroxyindole alkylamines.
It is suggested that caerulein and caerulein‐like polypeptides may have some function either in the regulation of secretory processes of the skin or in the exchange of water and electrolytes through the skin, or in both.
The effect of isoprenaline on adrenoceptors in human saphenous vein
Authors: COUPAR I. M. 
Published: July 2012

The order of potency of sympathomimetic amines in causing contraction of strips of human saphenous vein was (−)‐adrenaline>(−)‐noradrenaline>(−)‐phenylephrine>(±)‐isoprenaline.
The competitive α‐adrenoceptor blocking drugs tolazoline, phentolamine, and thymoxamine and the irreversible blocking drug phenoxybenzamine all blocked noradrenaline and isoprenaline contractions.
Contractions produced by 5‐hydroxytryptamine were also blocked by phentolamine and thymoxamine. Fenfluramine‐induced contractions were not blocked by thymoxamine or phenoxybenzamine.
ED50 contracting doses of isoprenaline did not cause consistent relaxation of noradrenaline‐contracted strips.
It is concluded that human saphenous vein contains a dominant population of α‐adrenoceptors which can be stimulated by high doses of isoprenaline, but the occurrence of β‐adrenoceptors mediating relaxation is rare.
The Schultz‐Dale response of the longitudinal muscle strip preparation of guinea‐pig ileum
Authors: DALE M. MAUREEN , ZILLETTI LUCILLA 
Published: July 2012

The mast‐cell distribution in the various layers of the ileum has been described.
Histamine‐content, anaphylactic histamine‐release and the anaphylactic dose‐response curve of the full‐thickness ileum and of the longitudinal muscle strip have been measured and compared.
Tetrodotoxin 10−7 g/ml had no obvious effect on the anaphylactic dose‐response curve of either preparation. This suggests that the plexus is not of any great importance in the Schultz‐Dale reaction.
Exposure of the longitudinal muscle strip to octylamine 10−3 g/ml for 1 min reduced the mast cell content by 95–100%. After this treatment the dose‐response curve to antigen was eliminated, although the muscle still responded to small doses of histamine and to anaphylactic mediators. Pre‐treatment of antibody with octylamine did not impair passive sensitization and subsequent response to antigenic challenge. This suggests that the classical Schultz‐Dale reaction in the strip is mediated mainly by mast cells, and possibly other cells, and is probably not due to a direct effect of the antigen‐antibody reaction on the smooth muscle.
The typical three‐phase anaphylactic response (quick contraction, quick relaxation, slow contraction) of full‐thickness ileum is discussed and compared with the predominantly two‐phase response of the longitudinal muscle strip. No evidence was found for the release of a relaxation‐factor. It is suggested that the initial fast phase may be due to mediators released from mast cells among the longitudinal muscle fibres, and the sustained contraction to a second wave of mediators reaching the longitudinal muscle from deeper layers of the ileum.
Comparison of the effects of propranolol and MJ 1999 on cardiac β‐adrenoceptors in man
Authors: EKUE J. M. KOFI , LOWE D. C. , SHANKS R. G. 
Published: July 2012

Summary. Propranolol, a β‐adrenoceptor blocking drug with local anaesthetic and a direct myocardial depressant action, and MJ 1999, a β‐adrenoceptor blocking drug which has no local anaesthetic or intrinsic sympathomimetic action, were compared for β‐adrenoceptor blocking activity in man.. Propranolol was 2·67 times more active than MJ 1999 in reducing by 50% the tachycardia produced by the intravenous infusion of isoprenaline in healthy volunteers.. Propranolol and MJ 1999 intravenously both reduced resting heart rate in the standing position and an exercise tachycardia, but there was no qualitative or quantitative difference between them.. On oral administration, both propranolol and MJ 1999 reduced resting heart rate and an exercise induced tachycardia; propranolol was only slightly more active than MJ 1999.. In patients with thyrotoxicosis propranolol was about twice as active as MJ 1999 in reducing the heart rate.
Comparison of the inotropic response to glucagon, ouabain and noradrenaline
Authors: SPILKER B. 
Published: July 2012

. The inotropic activity of glucagon was compared with catecholamines and cardiac glycosides by in vitro procedures which were able to differentiate between the activities of the latter two groups.
. The frequency‐force curve for glucagon resembled that of noradrenaline at low stimulation frequencies (1 and 2/min) and that of ouabain at more rapid frequencies of stimulation.
. Noradrenaline and adrenaline increased the amplitude of contraction of cat papillary muscles and markedly shortened the time to reach peak tension. Ouabain and glucagon increased tension without any change in the time to peak tension.
. Noradrenaline caused a rapid onset and rate of rise of contraction of cat aortic strips, whereas the response to ouabain was slow in onset and rate of development. Glucagon had no effect on this preparation, even at high concentrations.
. Manganese ions caused a shift of the dose‐response curve to ouabain and glucagon, but not to noradrenaline or calcium. In 0·5 mm Ca media, the response to ouabain was abolished and the curve to noradrenaline shifted.
. When glucagon was added to an atrial preparation, the time to the initial increase in tension and the time to maximal tension was intermediate between that necessary for noradrenaline and that necessary for cardiac glycosides.
. Propranolol blocked the inotropic response to noradrenaline, but not to either ouabain or glucagon.
. A relative measure of contraction‐dependency was described. Cardiac glycosides exhibited a greater degree of contraction‐dependency than either noradrenaline or glucagon.
. Adrenaline elevated the depressed plateau of the action potential from calf and sheep Purkinje fibres, but ouabain and glucagon were without effect.
. Electrophysiological measurements demonstrated that moderate concentrations of glucagon exerted only a small effect in prolonging atrial and ventricular action potentials.
. Several pharmacological blocking drugs and other inotropic agents did not potentiate or block the inotropic response to glucagon. Reserpine pretreatment increased the response to glucagon.
. It was concluded that glucagon has its own spectrum of inotropic activity and does not completely mimic the effects of either ouabain or noradrenaline.
Influence of pH on the inhibitory action of local anaesthetics on smooth muscle contraction
Authors: ANTONIO A. , ROCHA E SILVA M. , YASHUDA Y. 
Published: July 2012

. The guinea‐pig isolated ileum kept in a calcium‐free depolarizing solution contracts when calcium is added; the responses are proportional to the concentration of calcium and are reversed by washing.
. The contractions elicited by calcium are inhibited by three different classes of compounds: local anaesthetics, pentobarbitone and ethanol. The inhibitory action of the local anaesthetics increases with an increase in pH, the inhibitory action of pentobarbitone increases with a decrease in pH and the inhibitory action of ethanol is not affected by variations in Tyrode pH.
. It is suggested that the antagonists are active when unionized and that the inhibition is obtained when unionized compounds have dissolved in the lipid material of the cell membrane. The possible site of action of the antagonists is discussed.
Acceleration of noradrenaline biosynthesis in the guinea‐pig vas deferens by potassium
Authors: BOADLE‐BIBER MARGARET C. , HUGHES J. , ROTH R. H. 
Published: July 2012

Summary
. Increasing the concentration of KC1 in Krebs‐Henseleit bicarbonate solution enhanced the formation of 14C‐noradrenaline (14C‐NA) from 14C‐tyrosine in the guinea‐pig vas deferens. In 52 mm KC1 Krebs‐Henseleit solution the specific activity of the newly formed 14C‐NA was double that of controls.
. The rate of synthesis of 14C‐NA from 14C‐tyrosine was constant for up to 2 h in 52 mm KC1 Krebs‐Henseleit solution and for 4 h in unmodified Krebs‐Henseleit solution.
. There was no increase in NA formation in the presence of KC1 rich Krebs‐Henseleit solution if 14C‐DOPA was used as the starting substrate instead of 14C‐tyrosine.
. The specific activity of 14C‐tyrosine in the high KC1 treated vas deferens was 80% of that of control tissues. Thus the enhanced synthesis of 14C‐NA in high KC1 Krebs‐Henseleit solution did not arise from an increase in the specific activity of precursor.
. The effect of K+ on NA synthesis was not mimicked by ganglionic stimulants nor blocked by tetrodotoxin.
. Removal of Ca2+ ions or increasing the concentration of Mg2+ ions abolished the increase in synthesis of NA seen in high KC1 Krebs‐Henseleit solution but left the basal rate of NA synthesis in unmodified Krebs‐Henseleit solution unaltered.
. The spontaneous release of newly synthesized catecholamines (14C‐labelled) or tritiated noradrenaline (3H‐NA) from vasa deferentia was increased in 52 mm KC1 Krebs‐Henseleit solution. Removal of Ca2+ ions reduced the increased efflux of newly synthesized amine in high KC1 media to that seen in unmodified Krebs‐Henseleit solution. The efflux of 3H‐NA was reduced to one‐third of its former rate in the absence of Ca2+.
. High KC1 Krebs‐Henseleit solution caused a substantial contraction of the vas deferens which was not abolished by tetrodotoxin. Release of 3H‐NA paralleled the contractile response, and was likewise unaffected by tetrodotoxin.
. No evidence was obtained for any alterations in the activity of tyrosine hydroxylase, the rate limiting enzyme in the formation of NA from tyrosine, in homogenates of vas deferens which had been treated with 52 mm KC1 Krebs‐Henseleit solution.
. These results support the hypothesis that acceleration of NA synthesis occurs when tyrosine hydroxylase is freed from end‐product inhibition by the release of noradrenaline, brought about in this case, by high concentrations of KC1.
Effects of intraventricular 2,4,5‐trihydroxyphenylethylamine (6‐hydroxydopamine) on rat behaviour and brain catecholamine metabolism
Authors: LAVERTY R. , TAYLOR K. M. 
Published: July 2012

Summary
. 6‐Hydroxydopamine (200 μg injected intraventricularly) caused depletion of noradrenaline from all regions of rat brain within 2 h after injection but depletion of dopamine in the brain was observed only from 2 days after injection. Both catecholamines remained depleted for more than 32 days.
. Rats treated with intraventricular 6‐hydroxydopamine were sedated and lethargic, with reduced spontaneous and exploratory activity, for periods of up to 8 days after injection. Conditioned avoidance responding was abolished or reduced for a similar period.
. Intraventricular 6‐hydroxydopamine caused a prolonged reduction in the amount of labelled catecholamines in store 4 h following an intraventricular injection of 3H‐dopamine. During the first 6 h after 6‐hydroxydopamine injection, there was a marked increase in neutral and acid metabolites from the labelled catecholamines.
. A comparison of the behavioural and biochemical effects of intraventricular 6‐hydroxydopamine and reserpine suggests that both drugs affect catecholamine storage mechanisms but by different mechanisms. It was not possible from these experiments to correlate behavioural changes with either catecholamine storage or metabolism.
Stimulating action of atropine on the release of acetylcholine by rat cerebral cortex in vitro
Authors: POLAK R. L. 
Published: July 2012

Summary
In cortical slices from rat brain incubated in a medium containing the irreversible cholinesterase inhibitor, soman (0·005 mm) and a high concentration of KCl (25 mm), atropine exerts a stimulating action on the release of acetylcholine (ACh).
Two possible explanations for this action were examined. Atropine might expel ACh from the nerve endings by occupying its storage sites or it might prevent an inhibitory action of the released ACh on its further release by occupying muscarinic receptors at the presynaptic endings; its action would then be a kind of ‘disinhibition.’
The stimulating action of atropine on ACh release persisted during prolonged incubation (up to 3·5 h) provided choline was added to the medium. This finding would be difficult to explain if atropine acted by expelling ACh from its storage sites.
The stimulating action of atropine on ACh release was inhibited by oxotremorine and by methacholine, added to the medium in high concentrations. This finding is readily explained if atropine acts by ‘disinhibition.’
Antinociceptive activity of morphine after injection of biogenic amines in the cerebral ventricles of the conscious rat
Authors: SPARKES C. G. , SPENCER P. S. J. 
Published: July 2012

Summary
A simple cannula and a cannula guide for making injections into the cerebral ventricles of conscious rats are described.
Intraventricular injections of 5‐hydroxytryptamine (5‐HT) or of noradrenaline (NA) were without effect on the nociceptive threshold of rats.
Intraventricular injection of 5‐HT potentiated the antinociceptive effect of morphine. Reserpine pretreatment antagonized the antinociceptive effect of morphine; this effect was reversed by intraventricular injection of 5‐HT.
Intraventricular injection of NA attenuated the antinociceptive action of morphine but was without effect on the inhibition by reserpine of the antinociceptive effect of morphine.
Subcutaneous injection or slow intravenous infusion of either 5‐HT or NA (up to 300 μg/rat) were without significant effect on the antinociceptive effects of morphine.
Intraperitoneal administration of dopa increased the nociceptive threshold above normal, but reduced the antinociceptive effect of morphine. Intraventricular injection of either dopa or dopamine had no antinociceptive effect but inhibited that of morphine.
It is suggested that the antinociceptive effect of morphine may depend on the balance between the concentrations of 5‐HT and NA in the brain.
Effect of diuretics on mouse blood sugar following single dose administration
Authors: FOY J. M. , FURMAN B. L. 
Published: July 2012

Summary
Frusemide, in doses which were maximal or supramaximal in respect of its natriuretic, diuretic and kaliuretic properties, produced a dose dependent, transient hyperglycaemic response in the mouse.
Bilateral nephrectomy resulted in a complete abolition of the hyperglycaemic response.
The hyperglycaemic response was accompanied by a decrease in liver glycogen and was significantly attenuated by adrenalectomy, adrenal demedullation and pretreatment with dihydroergotamine (DHE).
In the nephrectomized mouse frusemide treatment produced a marked reduction in intravenous glucose tolerance and a reduction in the plasma concentration of immunoreactive insulin following glucose administration. The drug had no detectable effect upon insulin sensitivity.
Hydrochlorothiazide exerted no detectable effect on mouse blood sugar.
Ethacrynic acid hyperglycaemia was obtainable after intraperitoneal or intramuscular injection, but not after intravenous injection. Intravenously administered ethacrynic acid exerted no effect upon intravenous glucose tolerance or insulin sensitivity in the nephrectomized mouse.
Adrenoceptor functions in the cat choledochoduodenal junctionin vitro
Authors: PERSSON C. G. A. 
Published: July 2012

SummaryThe effects of α‐ and β‐adrenoceptor stimulating agents were investigated on three different kinds of preparation of the isolated sphincter of Oddi and on the duodenum of the cat.Adrenaline (1·5 × 10−7m–6·3 × 10−7m), noradrenaline (1·6 × 10−7m–6·3 × 10−7m), and tyramine (2·9 × 10−6m–5·8 × 10−6m) increased the activity and tonus of the sphincter musculature and decreased duodenal activity and tone. The effect on the sphincter resulted in increased resistance to flow through the sphincter. The excitatory effects on the sphincter were blocked by phenoxybenzamine (1·7 × 10−8m–1·7 × 10−7m).No effect was produced by tyramine in concentrations up to 4·6 × 10−5mon sphincters taken from reserpinized cats. It is suggested that the cat sphincter of Oddi contains adrenergic nerves of functional importance.Isoprenaline (1·9 × 10−8m–4·7 × 10−7m) and terbutaline (3·5 × 10−7m–8·8 × 10−6m) decreased spontaneous activity and tonus of the sphincter, and diminished resistance to flow through the sphincter. Both agents decreased spontaneous activity and tonus of the duodenum. On a molar basis, isoprenaline was 2–18 times more active than terbutaline on the sphincter and 35–90 times more active on the duodenum. The effects of isoprenaline and terbutaline were blocked by propranolol (3·9 × 10−7m).It is concluded that the cat sphincter of Oddi contains α‐adrenoceptors active in contraction of the sphincter, and β‐adrenoceptors active in its relaxation. The β‐adrenoceptors of the sphincter differ from those in the duodenum; it is suggested that they belong to the β2‐group (according to Lands' classification).The automaticity of the isolated sphincter of Oddi resembled the sphincter activity recordedin vivoand is probably myogenic in nature, as it resisted treatment with phenoxybenzamine (1·7 × 10−8m–1·7 × 10−7m), atropine (1·4 × 10−6m–5·8 × 10−6m), hexamethonium (1·4 × 10−5m–1·1 × 10−4m) and tetrodotoxin (1 μg/ml). The activity of the sphincter has no propulsive function but prevents passage of fluid through the sphincter.
Importance of the sympathetic nervous system in the development of renal hypertension in the rat
Authors: GREWAL R. S. , KAUL C. L. 
Published: July 2012

Summary
Chemical sympathectomy with 6‐hydroxydopamine (6‐OHDA) prevented the development of renal hypertension in 80% of weanling male rats of the C.F. strain.
Adult male rats treated with 6‐OHDA developed hypertension on bilateral clamping of the renal arteries.
Demedullation of the adrenal glands followed by 6‐OHDA treatment in adult rats prevented the development of hypertension in 75% of them.
Weanling rats treated with 6‐OHDA did not have any measurable catecholamines in their hearts up to 72–78 days after treatment.
Unlike the weanling rats, the hearts of adult rats (demedullated or with intact medulla) showed significant refilling (40–50%) of catecholamine stores 60 days after 6‐OHDA treatment.
It is concluded that the functional sympathetic nervous system is important in the development of renal hypertension in the rat.
Effect of thermal injury on the kinin system in rabbit hind limb lymph
Authors: LEWIS G. P. , WAWRETSCHEK W. A. 
Published: July 2012

Summary
The kinin‐forming activity of hind limb lymph and of plasma has been examined in rabbits before and after thermal injury.
Neither plasma nor lymph contained much active kallikrein activity but the enzyme was evident in samples treated with glass or with acid.
There was little or no increase in the activity of enzyme activated by glass after thermal injury, but an increase in the activity of enzyme activated by acid regularly occurred.
There were two increases in the activity of enzyme activated by acid—one about 2 h and the other 4–6 h after thermal injury. They corresponded to increases in vascular permeability as indicated by increases in the concentration of lymph protein.
There was considerably more kininogen in the lymph and plasma than was used in the assays of kallikrein activity, showing that the increased kinin‐forming activity in lymph was not the result of the passage of kininogen from the plasma.
The increase in activity in lymph was not usually accompanied by a similar increase in the plasma. However, an increase in the activity of enzyme activated by acid sometimes occurred in the plasma simply as a result of prolonged anaesthesia.
It is suggested that whereas the enzyme activated by glass is a measure of prekallikrein, the acid activatable enzyme appears as a result of the dissociation of a kallikrein‐inhibitor complex. An increase in the concentration of this complex is therefore an indication of the preceding activation of kallikrein.
Effects of isoprenaline and phenylephrine on energy‐rich phosphate compounds and glucose‐6‐phosphate in smooth and cardiac muscle
Authors: WESTON A. H. 
Published: July 2012

Summary
Tension changes produced by phenylephrine and isoprenaline have been examined in four tissues—the guinea‐pig taenia coli, the longitudinal muscle strip of rabbit duodenum, the abdominal aorta of the rabbit and the rat heart.
Changes in the amounts of adenosine triphosphate (ATP), creatine phosphate (CP) and glucose‐6‐phosphate (G‐6‐P) associated with the addition of phenylephrine and isoprenaline have been measured in the four tissues using enzymatic fluorimetric analysis.
An α‐adrenoceptor‐mediated increase in tension (phenylephrine; rabbit aorta) was associated with no change in the amounts of ATP, CP or G‐6‐P.
An α‐adrenoceptor‐mediated decrease in tension (phenylephrine; guinea‐pig taenia coli and rabbit duodenum) was associated with no change in the amounts of ATP, CP or G‐6‐P.
A β‐adrenoceptor‐mediated increase in force of contraction (phenylephrine and isoprenaline; rat heart) was associated with a reduction in the amounts of ATP and CP and an increase in the amount of G‐6‐P.
A β‐adrenoceptor‐mediated decrease in tension (isoprenaline; guinea‐pig taenia coli and rabbit duodenum) was associated with an increase in the amounts of ATP and CP and no change in the amount of G‐6‐P.
β‐Adrenoceptor‐mediated metabolic changes were antagonized by propranolol.