摘要:

AbstractThe effects on baroreceptor and sympathetic nerve activity of the a‐adrenergic blocking agent phenoxybemamirie have been investigated in 13 anesthetized rabbits. Nerve activities were recorded at various blood pressure levels, obtained by stepwise changes of blood volume. With phenoxybenzamine, aortic nerve activity at 80 and 90 mm Hg exceeded control values by 66 and 62 %. At the same pressures, renal nerve activity was reduced by 30 and 55 %. Although blood pressure started to fall shortly after injecting the drug, about 20 min elapsed before development of maximum effects on the nerves. When studied during stepwise changes of blood pressure after a similar period of hypotension—but without the drug‐sympathetic nerve activity had increased. Phenoxybenzamine had accordingly effected a suppression of sympathetic activity, suggesting that the hypotensive response to phenoxybenzamine is aided by increased reflex inhibition of sympathetic nerve act

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05280.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe influence of prolonged stimulation of the chordo‐lingual nerve (1 1/2–2 h) on secretion, blood flow and the content of kininogenase in cat submandibular glands has been studied. Quantitative estimation of hydrolysis of α‐N‐Benzoyl‐L‐Arginine Ethyl Ester (BAEE) at pH 8.5 was found to be a useful measure of total kininogenase activity. The volume of secreted saliva decreased throughout the period of chorda stimulation by as much as 30 per cent, while the salivary concentration of kininogenase was reduced by up to 80 per cent. The maximal increase in venous outflow as well as the duration of the chorda‐induced vasodilatation was also considerably reduced throughout the expermenrs. The kininogenase activity in the glands themselves was reduced by 20–40 per cent. Stimulation of the chorda caused a 15–80 per cent reduction of the kininogenase activity also in cats which had received atropine so that secretion of saliva was blocked. During activation of the submandibular gland a major part of the reduction in kininogenase activity may be explained by release of enzyme into saliva. However, since a substantial reduction in kininogenase activity was also found in activated, atropinized, non‐secreting glands, some enzyme appears to be released to the interstitial fluid, whereby kinin form

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05281.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe inhibitory effect of tricyclic neuroleptic and antidepressant drugs was investigated on the uptake of14C‐labelled 5‐hydroxytryptamine (5‐HT), dopamine (DA), noradrenaline (NA) and histamine (Hi) by isolated rat mast cells. All drugs inhibited the amine uptake but varied quantitatively and qualitatively in their blocking effects. Results showed that 5‐HT and NA uptake were competitively inhibited by both neuroleptics and antidepressants, whereas DA uptake only seemed competitively inhibited by neuro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05282.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe activity in unmyelinated afferents from left ventricular receptors was examined in cats during shortlasting general asphyxia and during transient occlusion of one coronary artery. After 40–70 s of asphyxia the receptors increased their activity. The firing initially displayed a cardiac rhythm but became continuous when the asphyxia was prolonged and intensified. This increased activity was closely related to a mechanical distension of the left ventricle when the nutritional supply was compromised suggesting a mechanoreceptor rather than a chemo‐receptor function of the recepton. Coronary occlusion also caused an activation of the ventricular receptors after a latency of about 35 s with an initial cardiac rhythmicity which became continuous with prolonged occlusions. The receptor activation appeared also in this situation to be caused by the mechanical bulging of the ischemic area of the left ventricular wall, rather than by chemical fact

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05283.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractEstimations of the average discharge rates in vasoconstrictor fibres to skeletal muscle, kidney, intestine and skin at varying levels of arterial baroreceptor activity were made by comparing quantitatively the reflexly induced vascular responses with those obtained with stimulations of the regional vasoconstrictor fibres at known frequencies. The results indicate that withdrawal of baroreceptor restraint was normally followed by a considerably lower firing rate in renal vasoconstrictor fibres than ine.g. skeletal muscle vasoconstrictor fibres. A complete elimination of the inhibitory influence induced vasoconstrictor fibre discharge rates up to 8 imp/s in skeletal muscle but only at most 4 imp/s in the kidney. Intestinal vasomotor fibres were found to be activated to approximately the same extent as those to skeletal muscle. The vasomotor fibres to the cutaneous arterio‐venous anastomoses were evidently not activated when the baroreceptors were unloaded. The reason for this non‐uniform activation of the different sets of vasoconstrictor fibres seems to be different levels of spontaneous activity in the respective “neuron pools” in the bulbar vasomotor centre. The renal vascular responses to baroreceptor unloading became augmented when the excitatory level in the vasomotor centre was enhanced, ase.g. when the animal became a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05284.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractMonophasic action potentials (MAP) were recorded by a suction electrode catheter which was pushed against the endocardial side of the free wall of the right ventricle in the dog heart in situ. The spatial and temporal distributions of the depolarization and repolarization processes were studied. The durations of the MAP recorded from different subendocardial areas of the ventricular wall showed no systematic differences. The excitation process spiead radially from the prepapillary region. During stimulation of the vagal nerves no change of the impulse propagation velocity or of the shape and duration of the MAP was observed. On endocardial, unipolar pacing in the prepapillary region of the right ventricle the excitation process in the free ventricular wall corresponded closely to that noted on spontaneous excitation; this electrode position also gave the shortest Q‐T interva

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05285.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe instantaneous relationship between isotonic load and velocity of shortening was studied in rabbit papillary muscles using a quick‐release technique which involved critical damping of the lever. The force‐velocity curve was determined from the experimental data by means of the least squares method using a computer program. The curve exhibited a true hyperbolic shape and virtually the same values of the constantsaandbin Hill's equation were obtained when the analysis was carried out during the rising or falling phase of an isometric contraction. The experimental basis of the discrepant results reported in previous studies has been scrutinized. Variability in active state intensity and contractile element length between individual force‐velocity determinations may account for the non‐hyperbolic shape of the force‐velocity curve obtained in an analysis of after loaded contractions. Quick releases performedwithoutcritical damping of the lever movements were found to have a depressant effect upon the myocardial activity resulting in a distortion of the force‐velocity curve at intermediate and small loads. The distortion of the curve was more pronounced when the analysis was carried out during relaxation than during the rising phase of the contraction. The deactivating effect is most likely attributable to the rapid fluctuations in speed of shortening of the contractile unit caused by inertial oscillations of the lever system after an underdamped qu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05286.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractDinitrophenol (DNP) was shown to have cardiac stimulant action on the isolated perfused guinea pig heart. The initial large increase in the force of contraction of the heart was followed by a smaller response which persisted throughout the DNP perfusion. On washout the activity of the heart returned to its previous level. Further DNP perfusion had no effect on the heart even though its amine level was not depleted. However, the positive inotropic effect of DNP reappeared in the heart after perfusion with noradrenaline (NA). Propranolol blocked the cardiac response to DNP. The metabolic uncoupler reduced the NA content in the heart and raised the amine level in the perfusate. The uptake of exogenous NA, and of14C‐NA, by the heart was not affected by low and high concentrations of DNP. The results suggest that DNP may have a direct action releasing NA from an extragranular poo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05287.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe fine structure of the paracervical ganglion was studied in the rat after 3 % KMnO4 fixation. Three types of neuronal cells were observed: (1) The majority of cells were devoid of dense‐core vesicles (DCV). (2) The minority of cells with typical neuronal structure contained small (500 A) and large (1000 A) DCV. (3) The cells resembling those of the adrenal medulla contained vesicles up to 3000 A in diameter with irregular and dense core. The synaptic axon terminals to the different cell types contained agranular vesicles. Because no small DCVs were found, these synapses are presumably not adrenergi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05288.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractContractions were induced by the synthetic C‐terminal octapeptide of cholecystokinin (C8‐CCK) in strips of guinea pig gall‐bladder in vitro. These contractions were relaxed by cyclic AMP (CAMP) and by agents known to increase the intracellular content of cAMP (isoprenaline and theophyllamine). The contractile response to C8‐CCK was preceded by an almost 50 per cent activation of the phosphodiesterase activity and a 67 per cent decrease of the cAMP content in the muscle. It is concluded that C8‐CCK lowers the content of cAMP in the guinea‐pig gall‐bladder muscle by activating phosphodiesterase. This metabolic response to C8‐CCK may be of importance for the development of the contr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb05289.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY