摘要:

SUMMARY1. The influence of dopamine, levodopa and apomorphine on sleep produced by pentobarbitone was studied in 1‐14 day old chicks.2. Pentobarbitone‐induced sleep was associated with synchronization of the electroencephalogram (EEG) of the hyperstriatum, optic tectum and pontine reticular formation.3. Dopamine desynchronized the EEG and antagonized pentobarbitone‐induced EEG synchronization.4. High doses of dopamine produced a delayed sleep which was potentiated by pimozide and antagonized by adrenoreceptor blocking agents.5. Dopamine, levodopa and apomorphine delayed the onset and shortened the duration of pentobarbitone‐induced sleep; apomorphine was the most potent.6. Pimozide prolonged the duration of pentobarbitone‐induced sleep, but had less effect when dopamine was a

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00068.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1.The mechanisms underlying the cardiovascular action of YC‐93, a new dihydropyridine vasodilator with cyclic AMP phosphodiesterase inhibitory activity, was investigated by comparing its effects wth those of papaverine in various isolated, blood‐perfused heart preparations of the dog.2. In all preparations YC‐93 injected into the nutrient arteries produced a dose‐dependent increase in blood flow, and in this respect YC‐93 was about twenty times more potent than papaverine on a weight basis.3. In sinoatrial node preparations YC‐93 injected into the sinus node artery decreased sinus rate in a dose‐dependent manner, and in large doses produced atrial standstill.4. In atrioventricular (a.v.) node preparations YC‐93 injected into the a.v. node artery increased a.v. conduction time in a dose‐dependent manner, and in large doses produced a second or third degree block of a.v. conduction. However YC‐93 injected into the anterior septal artery scarcely affected a.v. conduction.5. In spontaneously contracting papillary muscle preparations YC‐93 injected into the anterior septal artery failed to affect ventricular automaticity in doses which markedly decreased developed tension of papillary muscles.6. In papillary muscle preparations driven at a fixed rate YC‐93 injected into the anterior septal artery produced a dose‐dependent decrease in developed tension of papillary muscles.7. Unlike YC‐93, papaverine decreased a.v. conduction time in a.v. node preparations and increased developed tension of papillary muscle preparations.8. The cardiac effects of YC‐93 elucidated in the present experiments are characteristic of calcium‐antagonistic vasodilators. The action of YC‐93 as an inhibitor of cyclic AMP phosphodiesterase does not appear to

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. The action of angiotensin II on lung vessels was compared in dogs, cats, ferrets and rats using isolated perfused lungs and lobes of lungs perfusedin vivo, both at constant flow, so that increases in inflow pressure at constant outflow pressure indicated increases in resistance.2. Angiotensin II caused some increases in resistance in dogs, cats and rats but not ferrets. The increases were small compared with changes in the systemic circulation. Larger increases could be obtained in isolated lungs where there was no interference from rises in left atrial pressure.3. All four species showed pulmonary vasoconstriction during hypoxia and ferret lungs were especially responsive. Thus angiotensin II cannot be the mediator of hypoxic vasoconstriction in all these species.4. Angiotensin II significantly increased the response to hypoxia in isolated cat and rat lungs while also increasing baseline inflow pressure; the response to hypoxia was not altered in ferrets. Angiotensin II may therefore enhance reactivity of pulmonary vessels.5. Verapamil, an inhibitor of calcium transport across cell membranes, reduced the response to hypoxia in rats and ferrets more than it reduced the response to angiotensin II in rats or prostaglandin F2α in ferrets. Thus hypoxic pulmonary vasoconstriction probably involves transport of calcium

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. Cell proliferation in the jejunal crypts, the colonic crypts and in dimethyl‐hydrazine (DMH)‐induced adenocarcinomata of rat colon was measured using a stathmokinetic technique.2. Dibutryl cyclic adenosine monophosphate (dibutyryl cAMP) was found to inhibit cell proliferation in colonic crypts and in colonic adenocarcinomata.3. Dibutryl cAMP at very high doses was found to inhibit jejunal crypt cell proliferation but at lower doses was found to accelerate jejunal crypt cell proliferation.4. Neither bilateral adrenalectomy nor chemical sympathectomy was found to abolish the ability of dibutryl cAMP to stimulate jejunal crypt cell proliferation.5. The present results are difficult to interpret in terms of known hormonal influences on cell proliferation in the tissues examined and of established actions, of these hormones on cyclic nucleotide metabolism in other tiss

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. Two methods were used for altering blood pressure in conscious rabbits by up to ± 30 mmHg from the resting level in order to characterize the barorecep‐tor‐heart rate reflex. These were to inflate descending aortic or inferior vena caval cuffs, or to give brief intravenous infusions of phenylephrine or glycerol trinitrate. The relation of change in blood pressure to change in heart interval was examined, both during the initial ‘ramp’ changes of these variables and when they had reached a ‘steady‐state'.2. Both methods allowed the construction of'steady‐state’ sigmoid stimulus‐response curves whose parameters were reproducible within animals, and which were attended by a relatively small variance between animals. The inflatable‐cuff method gave a higher average value for maximum gain than the vasoactive drug method (10.0v5‐4 ms/mmHg) and a narrower pressure range between the threshold and saturation points of the response, but values for the other parameters were similar. Corresponding parameters obtained by the two methods correlated closely.3. After denervating all arterial baroreceptors except one carotid sinus, ‘steady‐state’ maximum gain by cuff‐inflation was reduced to 3.1 ms/mmHg, and to 2‐6 ms/mmHg by the vasoactive drug method. The heart interval range between upper and lower plateau levels was reduced, but the pressure range between threshold and saturation points was widened, with both methods.4. During the initial ‘ramp’ changes of blood pressure the sensitivity of the reflex was described by the slope of the linear regression of heart interval on ‘mean blood pressure. The slopes obtained by aortic cuff inflation, and by infusion of either vasoactive drug, correlated positively with ‘steady‐state’ maximum gain. However, the reproducibility of the ‘ramp’ method was inferior to that of the ‘steady‐state’ method with respect to reflex sensitivity, and other parameters of the stimulus‐response relation cannot be estimated.5. Complete baroreceptor denervation virtually eliminated heart rate changes over the range of blood pressures usually employed. However, when blood pressure was increased by more than 40 mmHg a pr

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. In two experiments severe hypertension (systolic blood pressure 180 mmHg) was induced in rats by constricting one renal artery with a silver clip (two‐kidney, one clip hypertension; 2KIC). Blood pressure, plasma renin activity (PRA) and body weight were measured for 35 days after clipping. Plasma sodium concentration and carcass sodium content were measured at the conclusion of the experiment. To determine the relationship between sodium intake, PRA and the development of severe hypertension, half of the rats were given a normal diet and water to drink; the other half were given a low sodium diet and 0‐9% saline to drink.2. In both experiments, two patterns of responses were observed. Group (1) had reduced growth rate, and marked elevation of PRA. Some, but not all of these animals had histological evidence of malignant nephrosclerosis in the untouched kidney. In the other group (11), weight gain was normal and PRA was normal or only slightly elevated.3. Group 1 animals drinking saline, had raised carcass sodium levels, whereas those drinking water had no increase in carcass sodium.4. The results confirm that hypertension in the 2KIC model is not always associated with a raised PRA.5. The coexistence of a raised PRA and increased total body sodium suggests that the PRA does not rise as a result of sodium depletion in this mo

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. Morphine pretreatment (8 0 mg/kg s.c.) induced no overt tolerance to its antinociceptive effect in mice 4 h later, but enhanced the antagonistic potency of naloxone.2. A molecular sieve morphine pellet implanted for 24 h induced measurable tolerance, but the relative potency of naloxone was not significantly different from that observed after single‐dose morphine pretreatment. The development of tolerance and increased naloxone potency do not, therefore, run parallel.3. Naloxone‐precipitated withdrawal symptoms were observed after single‐dose morphine and after pellet implantation. However, molecular sieve morphine pellet implantation induced a higher degree of dependence as compared with single dose morphine pretreatment.4. These results indicate that the rate of development of increased naloxone potency and of morphine tolerance and dependence do not run parallel. This implies that caution must be exercised in regarding increased naloxone potency as a sensitive indicator of the initiation and development of tolerance and dependence to mor

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. Plasma renin and arterial pressure responses to acute renal artery pressure reduction were compared in intact dogs and ‘autonomically‐blocked’ dogs subjected to adrenalectomy, chronic guanethidine treatment and acute vagal block (methscopolamine).2. Following reduction of renal artery pressure plasma renin activity and concentration rose more in the autonomically blocked dogs than in the intact dogs. When renal artery pressure was held at 30 mmHg for 1 h, plasma renin activity rose by 19‐1 ng/ml per h (range 11‐6‐28‐7) in autonomically blocked dogs and 3‐65 ng/ml per h (range 1‐54‐5‐89) in intact dogs. When renal artery pressure was held at 60 mmHg plasma renin activity rose 3‐28 ng/ml per h (range 2‐4‐4‐7) and 1‐90 ng/ml per h (range 1‐30‐3‐56), respectively.3. Arterial blood pressure also rose more in autonomically blocked dogs in accord with the greater rise in plasma renin activity. The relationships between the increases in arterial pressure and plasma renin were closely similar in the two groups.4. We conclude that the relase of renin and increase in arterial blood pressure in response to renal artery stenosis is normal

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. A colloidal bismuth preparation, tripotassium dicitrato‐bismuthate, was given (172 mg/kg body weight, 6/7 days) to 10 laboratory rats for 14 months. Bismuth was measured by atomic absorption spectrometry in various tissues and the pattern of distribution studied.2. Bismuth was present in kidney, lung, spleen, liver, brain, heart and skeletal muscles, in descending order of abundance. Haematological data, renal and liver function tests were normal in the bismuth‐treated group.3. The data suggested that chronic ingestion of bismuth in large doses in rats results in absorption and binding to tissues. Absorbed bismuth probably crosses the blood‐brain ba

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARY1. In anaesthetized kittens, Cortisol (16 mg/kg) potentiated peak chronotropic responses to isoprenaline but did not affect peak bronchodilator responses to this amine.2. In contrast, the duration of both chronotropic and bronchodilator effects of isoprenaline were clearly potentiated by Cortisol.3. These results have been linked with cortisol‐induced inhibition of3H‐iso‐prenaline uptake in the perfused kitten heart and isolated tracheal smooth m

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1980.tb00077.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY