摘要:

SUMMARY1. In previous studies, exogenous serotonin (5‐HT), administered intravenously, caused dose‐related increases in mean arterial pressure and heart rate in conscious sheep. The 5‐HT2antagonist ketanserin (0.1 mg/kg per h, i.v.) was shown to lower blood pressure in the conscious sheep primarily through antagonism of α‐adrenoceptors.2. A newer 5‐HT2antagonist, ritanserin, is a more selective antagonistin vivo, as it attenuated or abolished pressor responses to exogenous 5‐HT, but not to phenylephrine.3. When infused alone, ritanserin (0.1 mg/kg per h, i.v.) failed to produce a decrease in blood pressure, suggesting that 5‐HT antagonistic properties are not sufficient by themselves to lower blood pressure.4. Ritanserin displayed a different metabolic profile to ketanserin, with a markedly decreased water intake. The mechanism of this effect is unresolved, but may imply a permissive role for 5‐HT in the modulation of drinking responses in the sheep.5. Ritanserin did not modify ACTH‐induced hyp

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01874.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. To determine whether increasing dietary potassium alters kallikrein activity or prostaglandin synthesis, 77 women participated in a 3 week screening to assess their dietary potassium intake. Forty‐four normotensive women whose dietary potassium was less than 60 mmol/day were allocated randomly to one of two groups who took either 80 mmol/day KC1 (Slow‐K, Ciba Geigy) or matching placebo for the first or second of two 4 week periods.2. Significant increases in urinary kallikrein excretion (P<0.01), and urinary 6‐keto‐PGF1α(P<0.01) were observed during potassium supplementation. These changes occurred without alterations in urine volume or sodium excretion.3. It is suggested that potassium‐induced changes in urinary 6‐keto‐PGF1αmay reflect increased renal and possibly vascular synthesis of prostacyclin. These increases may be mediated by increased plasma potassium stimulating kallikrein synthesis, leading to bradykinin‐induced activation of phospholipase A2. Enhanced kallikrein/kinin and prostacyclin formation could contribute to the blood pressure lowering effect of potassium reported in hype

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01875.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Cyclosporin A (CyA; 12 mg/kg/day) was infused into six conscious sheep over 5 days to examine the haemodynamic effects of the drug in normal animals.2. Mean arterial pressure was increased from 73(1) mmHg to 90(4) mmHg (P<0.001). There was no change in cardiac output but calculated total peripheral resistance was elevated from 16(1) to 21(2) mmHg min/1 (P<0.001) on day 4.3. There was no change in plasma [Na], but a fall in plasma [K]. Urinary Na excretion decreased. Glomerular filtration rate, filtration fraction, renal blood flow, renal vascular resistance, body weight, plasma renin and blood aldosterone concentration were unchanged.4. CyA produces an increase in blood pressure in sheep associated with an increase in total peripheral resistance on days 1, 3, and 4, in the absence of changes in renal function. This suggests that CyA hypertension is not simply a consequence of nephrotoxicity.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01876.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The effects of isoprenaline and (±)‐pindolol on rat isolated costo‐uterine muscle have been compared.2. Isoprenaline produced reproducible concentration‐dependent inhibition of contractions, and maximal doses (<0.1 μmol/l) produced mean inhibition of 87, 94 and 97% of field, carbachol and potassium‐stimulated preparations, respectively.3. (±)‐Pindolol, when effective, produced inhibition only in concentrations greater than its pA2value (9.87) as an antagonist of isoprenaline; mean maximal effects were<60% of those produced by isoprenaline.4. It is concluded that (±)‐pindolol is a potent antagonist, but has only variable agonist action, at the β2‐adrenoceptors of the rat co

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01877.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The reproducibility of pressor response to handgrip performed at different time intervals and with different combinations of the product duration × strength of the exercise was evaluated in 14 normotensive subjects recording blood pressure with a non‐invasive automatic device.2. Subjects underwent five consecutive tests (30% of maximal voluntary contraction × 90 s) at 30 min, and 24 h intervals and repeated the test after 12 months. Furthermore, they underwent at 24 h intervals a randomized sequence of handgrip tests whose product strength × duration was combined in order to achieve either a constant or an increasing level of exercise.3. Blood pressure response to exercise performed at 30 min intervals was much less reproducible than that induced by handgrip performed at time intervals ≥ 24 h.4. Increasing gradually the product strength × duration of the handgrip test there was a proportional blood pressure increase, whereas when the product was maintained constant diastolic blood pressure increase was also constant and reproducible within each subject.5. This study shows that it is possible to obtain reproducible diastolic blood pressure responses to handgrip test measuring blood pressure with a non‐invasive automatic device when the tests are performed at a time interval of at least 24 h. The choice of the strength and of the duration of the exercise is very important for the reproducibility of

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01878.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Plasma levels of atrial natriuretic peptide (ANP) are high in many patients with tachycardia, but patterns of release with onset and termination of tachycardia and relationships to haemodynamic recordings are not clear. Blood for ANP measurements was therefore drawn from the coronary sinus, femoral artery and femoral vein, and simultaneous haemodynamic recordings were made in five patients before, during and after induction of stable ventricular tachycardia for 30 min.2. Tachycardia induced increases in ANP to peak levels, 2.6 to 5.7 times higher than baseline values at 20 min or later, whereas maximum haemodynamic changes, including a rise in pulmonary artery diastolic pressure, were achieved within 4 min.3. Reversion to sinus rhythm resulted in immediate changes in haemodynamic recordings, whereas ANP levels in arterial and venous plasma fell sluggishly with an apparent half‐life of 9.6 and 7 min, respectively.4. The results support a central role for atrial pressure in determining ANP secretion, but demonstrate a temporal delay between changes in atrial pressure and ANP secretio

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01879.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Certain commercial preparations of oxytocin have been reported to reverse the development of pale soft exudative meat and malignant hyperpyrexia (MH) in pigsin vitro.2. In this study it is shown that preservative‐free oxytocin has no significant effect on the characteristic contractures of MH susceptible (MHS) muscle to halothane, caffeine, succinylcholine and KClin vitro.3. Whilst a commercial preparation of oxytocin, Syntocinon (containing chlorbutol as preservative), reversed and prevented the MHS characteristic responses, this study demonstrates conclusively that this was entirely due to the preservative chlorbuto

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01880.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The effects of the intrahippocampal injection of ethylcholine mustard aziridinium ion (AF64A) on the following cholinergic markers were examined.2. Bilateral injection of 10 nmol of AF64A into the dorsal hippocampus caused a loss of choline acetyltransferase (CAT) activity in the dorsal hippocampus, ventral hippocampus, cortex and striatum.3. This treatment caused significant decreases in ACh contents in the dorsal hippocampus, ventral hippocampus and cortex, but not in the striatum.4. The step‐down latencies during the test trials of both 10 and 50 nmol AF64A‐treated groups were significantly shorter than those of vehicle‐treated groups.5. None of the control animals stepped down to the large box where they had previously received a foot shock, but 40% of the 10 nmol and 60% of the 50 nmol AF64A‐treated animals stepped down to the large box within 600 s.6. These results indicate that AF64A treatment produces biochemical and functional deficits in the cholinergic neurons in

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01881.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. A study was made of venoconstrictor mechanisms in the hindquarters region of cats and dogs by the use of autoperfused hindquarter preparations, together with the measurement of vena cava blood flow (VCBF).2. Noradrenaline, adrenaline and angiotensin II (AII) were all administered intraarterially and their ability to alter perfusion pressure and VCBF was examined.3. All three drugs increased perfusion pressure in both cats and dogs as a result of increases in arterial resistance. At the same time, noradrenaline and adrenaline increased VCBF in cats, while AII had a variable effect. In contrast, all three drugs decreased VCBF in dogs.4. These differences in the venoconstrictor responses obtained in cats and dogs may be explained by an action of the drugs at different loci within the venous compartment of the two species.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01882.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY