摘要:

SUMMARY1. The effects of the calcium antagonists verapamil and nifedipine on mean arterial blood pressure, heart rate and pressor responses to a range of α‐adrenoceptor agonists were examined in male normotensive New Zealand white rabbits and in rabbits with perinephritis hypertension.2. Verapamil and nifedipine caused a greater fall in mean arterial pressure in hypertensive compared to normotensive rabbits both when the fall was expressed as an absolute and as a percentage change. Effects on heart rate were similar in normotensive and hypertensive animals.3. Pressor responses to phenylephrine were attenuated by nifedipine and verapamil in normotensive and hypertensive rabbits. Pressor responses to alphamethyl noradrenaline were also attenuated by nifedipine, but pressor responses to BHT 920 were not significantly altered by either calcium antagonist in normotensive or hypertensive rabbits at the dose used. Thus the calcium antagonists had a greater effect on α1‐than α2‐adrenoceptor mediated responses in both normotensive and hypertensive rabbits.4. Hypertensive animals showed an increased responsiveness to phenylephrine and alphamethyl noradrenaline but not BHT 920 compared to normotensives. This difference remained after treatment with both the calcium ant

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00960.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Sixteen stable asthmatics had the protective effects of inhaled fenoterol (200 μg) and inhaled ipratropium bromide (60 μg) against standardized histamine inhalation tests at 1 h examined in a randomized double blind fashion.2. There was no significant difference in the baseline forced expired volume in 1 s (FEV1) for the two study days (P>0.05).3. There was an increase in FEV, at 1 h on the fenoterol and ipratropium day compared with the fenoterol day (0.26 versus 0.17 1;P<0.05).4. The geometric mean provocative concentration of histamine to cause a 20% fall in FEV, (PC20) was 6.31 mg/ml after fenoterol and 8.51 mg/ml after fenoterol and ipratropium (P= 0.038).5. There was no significant relationship between bronchodilator effect of the bronchodilators and the increase in PC20from pre‐study values,r= 0.307 (P=0.25) for fenoterol alone andr=0.195 (P=0.47) for fenoterol and ipratropium.6. The relationship between pre‐study histamine responsiveness and the increase in PC20caused by the bronchodilators just failed to reach statistical significance,r= ‐0.441 (P= 0.09) for fenoterol alone andr= ‐0.47 (P=0.06) for fenoterol and ipratropium.7. The study has shown a greater right shift of histamine responsiveness for combined inhaled fenoterol and ipratropium compared with inhaled fenoterol alone in this group of a

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00961.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. A specific and sensitive radioimmunoassay has been developed and used to measure circulating atrial natriuretic peptide (ANP) in normal man and in patients with chronic renal failure.2. Circulating ANP levels rose with head‐down tilt and exercise, and were raised in patients with chronic renal failure in proportion to volume status. This suggests that ANP release is mediated via increased atrial stretch, although other release mechanisms cannot be excluded.3. Extracts of normal human plasma subjected to reverse phase HPLC showed one major peak of immunoreactivity co‐migrating with α‐human ANP. However, when plasma extracts from patients with renal failure were chromatographed on a similar system, a second later eluting peak of ANP immunoreactivity was observed. This may represent circulating ANP precursors or degradation molecules.4. Significant arteriovenous differences in plasma ANP concentration were observed in patients with chronic renal failure. Arterial and venous plasma ANP levels decreased slightly after haemodialysis. Plasma ANP concentrations were inversely correlated with haematocrit in these pa

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00962.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The effect of β‐adrenoceptor blockers on the absorption and elimination of the diuretic chlorothiazide was studied in healthy subjects.2. A week of pretreatment with either pindolol (10 mg twice daily) or propranolol (80 mg twice daily) resulted in significant reduction in 36 h mean cumulative urinary recovery of chlorothiazide in two groups of six subjects compared with a control (untreated) group.3. A week of pretreatment with atenolol (100 mg daily) did not significantly alter 36 h cumulative urinary excretion in another group of six subjects.4. None of the β‐blockers significantly changed chlorothiazide half‐life.5. It is suggested that the non‐selective (as opposed to the cardioselective) β‐blockers reduce chlorothiazide absorption by the mechanism(

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00963.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The roles of, and interactions between, steroids and naloxone, an opioid antagonist, in the reversal of experimental hypotensive shock were studied in normal and adrenalectomized rats.2. In normal rats treated with dexamethasone or deoxycorticosterone or 17‐hydroxyprogesterone the hypotension and shock caused by 1% bodyweight and 2% bodyweight haemorrhage could be substantially reversed by naloxone in a dose‐related manner. In contrast, the reversal of hypotension by naloxone was markedly less in adrenalectomized rats.3. It is concluded that there is a co‐ordinate release of pressor catecholamines and depressor enkephalins from adrenal glands in hypovolaemic shock. Eventually, the use of naloxone would be of much less value in the treatment of hypotension or shock in patients with Addison's di

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00964.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The antimicrotubule reagents, colchicine, griseofulvin, nocodazole, podophyl‐lotoxin and taxol had no effect on transferrin endocytosis or iron uptake by rabbit or rat reticulocytes but were inhibitory when used at high concentrations with rat fetal liver erythroid cells. The results imply that microtubules do not have a role in endocytosis and iron uptake by reticulocytes but may have a permissive role in the fetal cells.2. The only reagent found to inhibit iron uptake by reticulocytes was vinblastine. It was shown to act by inhibiting the endocytosis of transferrin.3. It is concluded that this effect is not the result of an interaction with microtubules, but may result from a non‐specific action on the cell membrane or a more specific effect, such as inhibition of calmodu

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00965.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Microinjections of kainic acid were made into the pressor area of the rostral ventrolateral medulla oblongata of anaesthetized rabbits, in the region of the C1 adrenaline‐containing neurons.2. Over the 65 min following the microinjection, there was a significant increase in blood pressure, as well as an increase in the release of neuropeptide Y‐like immunoreactivity into the spinal subarachnoid space.3. These data provide evidence for a functional bulbospinal neuropeptide Y‐containing projection which may be responsible for mediating the pressor effects of stimulation of the rostral ventrolateral me

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00966.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Haemodynamic and hormonal effects of doxazosin, a long‐acting α1‐adrenoceptor antagonist (2 mg) were compared with placebo in six normal men.2. Doxazosin at 2 mg produced lower supine systolic blood pressure and plasma cortisol concentration than control at 4 h only, but these changes were not sustained. Both supine and standing pulse rate were increased by active drug after 6 h.3. In this acute study doxazosin did not affect plasma renin or aldosterone concentrat

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00967.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The hemodynamic responses to i.v. infusion of 0.3 and 0.6 μg/kg per min of human atrial natriuretic factor (hANF [102–126]) in intact, conscious, one‐kidney, perinephritic, hypertensive beagles were examined and compared with the responses in ganglionic‐blocked dogs.2. Blood pressure and heart rate were not affected but plasma ANF‐like immunoreactivity was increased by as much as 627%.3. After hexamethonium (20 mg/kg, i.v.) blockade, a dose‐dependent hypotensive response of up to 29 mmHg with no change in heart rate was observed.4. It is concluded that the compensatory mechanisms of the neurally mediated baroreflex system masked the depressor actio

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00968.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe hypertensive effect of bromocriptine in young (6 week old) spontaneously hypertensive rats (SHR) was studied. Blood pressure and plasma norepinephrine level in bromocriptine‐treated SHR were significantly lower than those in vehicle‐treated SHR after 3 weeks of treatment (5 mg/kg per day, i.p.), while no significant decrease of blood pressure or plasma norepinephrine level was observed after 2 weeks of treatment. These results suggest the involvement of sympathetic nervous system inhibition in the hypotensive effect of bromocriptine in

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb00969.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY