摘要:

AbstractThe formation of alanine, glutamate, and aspartate from muscle was studied in the isolated perfused hind‐quarter of rats fasted for 48 h. Tracer doses of (14C) compounds with high specific activity were tested as precursors for the amino acids. Total amounts and radioactivities of the tested amino acids were determined. Alanine was produced more efficiently than glutamate and aspartate even if no exogenous substrate was offered. (14C) Pyruvate was most efficient as precursor of labeled alanine. However, labeled leucine, propionic acid, valine and fumaric acid also produced labeled alanine efficiently. The efficiency as precursor for labeled alanine seemed to be related to the ability to label intermediates in the citric acid cycle in the perfused muscle. From the relation between the ability to label alanine in the perfusion medium and lactate and succinate in the muscle it is suggested that pyruvate may be produced intramitochondrially and is efficiently transaminated to alanine in this compartmen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10264.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractIn acute spinalized (Th 12) cats, treated with DOPA, curarized or with all lumbosacral dorsal roots transected, stepping patterns were elicited in the hindlimbs by continuous electrical stimulation of the dorsal roots. Single primary endings in dorsal root filaments or single γ and α efferents in muscle nerve filaments from flexors and extensors were recorded together with the efferent nerve activity to various hindlimb muscles. The experiments showed a clear coactivation of the intra‐ and extrafusal system to the same muscle. The α efferent discharges typically started with a very short first interspace interval. It is concluded that there exists a central spinal α‐γ‐Iinkage for locomotion in the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10265.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe autonomic nerve control of the swimbladder of the goldsinny wrasse has been studied by experiments with isolated strips from the muscularis mucosae, drug effects on gas secretionin vivo, fluorescent histochemistry and quantitative analysis of catecholamine content. Vagotomy, atropine and mecamylamine significantly inhibited induced gas secretion, suggesting a cholinergic vagal secretory innervation of the gas gland. The anterior part of the mucosa (secretory part) is contracted by acetylcholine and α‐adrenoceptor agonists. These responses are competitively antagonized by atropine and phentolamine or yohimbine respectively. The posterior (resorbent) part of the mucosa is contracted by acetylcholine, but β‐adrenoceptor agonists relax the acetylcholine‐precontracted preparations. These responses are competitively blocked by atropine and propranolol respectively. The pA2‐values from all experiments with antagonists are well comparable with values obtained for the same drugs in other teleost or mammalian tissues. Tyramine, 5‐hydroxytryptamine or phenylephrine had mixed effects on the posterior part. This effect is at least in part due to release of nervously stored catecholamines. Fluorescent histochemistry revealed a strong innervation by both smooth and varicose adrenergic fibres in all parts of the swimbladder, noradrenaline being the dominant catecholamine. Yellow fluorescent cells, which may contain 5‐hydroxytryptamine, were also seen in the swimbladder mucosa. No conclusive evidence for a cholinergic innervation of the muscularis mucosae

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10266.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe intra‐axonal transport of acetylcholine (ACh) and ACh‐metabolizing enzymes in rat sciatic nerves was studied following nicotine treatment. The nicotine was administered in a low dose (30;μg/kg) s.c. every second h for 18–22 h, to mimic the serum‐concentrations of a cigarette smoker. Control rats received s.c. injections of the vehicle. The main effects were observed regarding the ACh‐esterase (AChE) activity. In unoperated nerves the level was decreased by about 10%. In 12 h crushed nerves the accumulation of enzyme activity proximal to the crush was markedly reduced in the nicotine‐treated group, indicating a reduction in amount of proximo‐distally transported enzyme activity. The ACh‐levels were unchanged except at 12 h postoperatively when a small increase proximal to the crush was observed. The choline‐acetyltransferase (CAT) activity in unoperated nerves was similar in both groups of rats; the 7 h accumulation above the crush, however, was somewhat reduced after nicotine treatment. The possible causes of the observed nicotine induced changes ar

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10267.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe influence of temperature on the time course of the mechanical activity was investigated in isolated papillary muscles of the rabbit. By using the “damped release” technique activity curves were determined in terms of velocity of shortening of the contractile unit at a constant length. At any of the temperatures studied, the time course of the mechanical activity exhibited a slow onset and did not form a distinct plateau. At low contraction frequencies and normal (2 mM) calcium concentration lowering the temperature from 32.5 to 26.5°C did not markedly affect the rate of development of the activity but increased the peak amplitude and the total duration of the activity as well as the time from the stimulus to 90 % of the maximum. It also resultedi n a slower decay phase. At higher contraction frequencies and/or increased calcium concentration the rate of development of the activity was reduced by decreasing the temperature from 32.5°C to 26.57deg;C., whereas the maximal activity reached similar levels at the two temperatures. It is concluded that an alteration in temperature affects several different steps in myocardial excitation‐contraction coupling, the net change in maximum amplitude of the mechanical activity being influenced by both extracellular calcium concentration and contraction fr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10268.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractVasoconstriction due to parallel i.a. injections of NA were studied in subcutaneous adipose tissue and gracilis muscle preparations in dogs. The vasoconstrictor response to NA was significantly lower in adipose tissue than in muscle. Only in muscle did acidosis inhibit NA‐induced vasoconstriction. The β‐receptor antagonist propranolol increased the vasoconstrictor response in adipose tissue to the level of skeletal muscle. The lack of significant inhibition of NA‐induced vasoconstriction in adipose tissue may be due to the simultaneous inhibition of two opposing mechanisms‐α‐adrenergic vasoconstriction and β‐adrenergic vasodilatation. After propranolol acidosis inhibited NA‐induced vasoconstriction equally in adipose tissue and muscle. The difference between adipose tissue and muscle may thus be due to a greater importance of a β‐adrenergic vasodilator mechanism in the former tissue. The metabolic response to isoprenaline was inhibited by acidosis, while the direct vasodilatation was unaffected. It is suggested that the β‐adrenergic vasodilator mechanism that is inhibited by acidosis is related to the me

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10269.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe response of isolated brain vessels to various pH levels or carbon dioxide tensions was analyzed. Reduction of the pH induced a slight relaxation of the vessel, whereas an increase in the pH produced a slight contraction. These effects were markedly exaggerated when the alpha‐adrenergic receptors in the vascular wall were activated by noradrenaline. During these conditions the contractile response to noradrenaline was reduced by about 40 per cent at a pH of 7.01, while, on the other hand, the response was enhanced 3‐fold at a pH of 7.80. Variations in carbon dioxide tension of the buffer solution between 16 mmHg and 64 mmHg produced no consistent change, provided the pH remained constant. The results indicate that an interaction between the perivascular pH and the adrenergic alpha‐receptor mediated contraction in brain vessels may

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10270.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe exteroceptive influences on tonic activity and on stretch reflexes of the longissimus dorsi and multifidus spinae muscles were investigated in decerebrate, spinal and chloralose‐anesthetized cats. Adequate skin stimulation was used to map out facilitatory and inhibitory skin areas on the trunk and the extremities. On the trunk facilitatory areas are relatively large and located at the dorsal side while inhibitory areas are confined to the ventrolateral part of the contralateral body half. The facilitatory skin fields are of approximately the same size in decerebrate and spinal cats. On leg skin stimulation facilitation can be evoked from the ipsilateral hind limb while inhibition results from stimulation of the other limbs. Spinal cord transection increased excitatory effects of ipsilateral hind limb stimulation. Reflex responses in the back muscles to applied stretch are described. These reflexes were used as test reflexes in experiments with conditioning stimulation of the peripheral nerves supplying skin areas from which effects on back muscle activity were evoked by adequate stimulation. The conditioning‐test experiments and those using adequate stimulation show that the longissimus dorsi and multifidus spinae are activated or facilitated by an ipsilateral stimulus to skin afferents. The extent of the effects induced by stimulation of skin differs in the types of preparation used. These differences may be accounted for by assuming a supraspinal control of the reflex pathways stud

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10271.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractBradykinin, oxytocin, physalaemin and some autonomic drugs were injected into the common carotid artery. Physalaemin evoked secretion and a pressure rise in the submaxillary duct. A duct pressure rise could be elicited by bradykinin which did not evoke secretion. Autonomic blocking agents did not diminish secretion evoked by physalaemin and did not change pressure responses elicited by bradykinin or physalaemin. Neither secretion, nor duct pressure changes could be recorded after administration of oxytocin. In agreement with previous experiments secretion evoked by autonomic drugs was found to be mediated via cholinergic, α‐ and β‐adrenergic receptors, while motor effects were due to activation of cholinergic and a‐adrenergic re

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10272.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractGastrin release and gastric acid secretion were induced by electrical stimulation of the vagi in anesthetized cats. No correlation was found between the peripheral gastrin levels and the magnitudes of the concomitant secretory responses. In experiments in which a high rate of secretion was induced the peripheral gastrin levels were found to be unchanged or at most slightly elevated, whereas the levels were sometimes substantially elevated in animals in which there was little or no acid secretory response.An arterio‐venous difference in gastrin levels was detected in the corpus blood during periods of gastric secretion. This clearance of gastrin (104–540 pg/min) was large enough to influence the peripheral gastrin levels. The mechanism behind and the significance of the gastric clearance of gastrin is discus

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10273.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY