摘要:

SUMMARY1. In two separate studies using healthy male smokers as subjects, the acute cardiovascular effects of a measured dose of nicotine (15 μg/kg) were examined in conjunction with light physical activity and following consumption of a meal, conditions typical of nicotine intake via smoking.2. Increases in heart rate and systolic blood pressure attributable to nicotine were similar during rest, physical activity, and following eating, demonstrating additivity with the cardiovascular effects of activity and a caloric load. Diastolic blood pressure was less affected by nicotine.3. These results indicate that cardiovascular activity is acutely increased following nicotine (smoking) regardless of other influences on the cardiovascular system. Such effects may help explain increased risks of acute cardiac abnormalities due to smoking

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01329.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. We investigated the mechanism of tetradecapeptide‐induced vasoconstriction by studying the metabolism of tetradecapeptide (TDP), angiotensinogen, and angiotensin I (AI) and angiotensin II (AII) by isolated perfused rat hindlimbs.2. Using HPLC and specific RIAs we have quantified six angiotensin peptides: pentapeptide(4–8), hexapeptide(3–8), heptapeptide(2–8), octapeptide(1–8), nonapeptide(2–10) and decapeptide(1–10) in hindlimb effluent.3. TDP‐induced vasoconstriction was associated with generation of predominantly AI and AII, with smaller amounts of the other peptides measured.4. Captopril prevented vasoconstriction and inhibited AII production by 80%, indicating a dominant role for AI generation in the vascular response to TDP.5. Evidence that renin is not the enzyme responsible for AI generation from TDP includes: first, the failure of angiotensinogen to cause vasoconstriction or angiotensin peptide generation despite very high amounts of AI and AII generation from TDP; second, the resistance of the TDP‐induced vasoconstriction and angiotensin peptide generation to inhibition by pepstatin; and third, the failure of bilateral nephrectomy 24 h before the experiment to influence the vascular and angiotensin peptide response to TDP.6. AII was cleared with 41% efficiency, with generation of penta‐, hexa‐, and heptapeptides.7. AI was cleared with 59% efficiency; this was reduced to 24% by captopril, indicating a conversion of at least 35% of AI to AII by ACE.8. These studies have identified vascular metabolism of AI and AII to be an efficient process, with both ACE and aminopeptidases playing an important role, and indicate that those peptidases which cleave TDP to generate AI are unlikely to play any role in

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01330.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. The effects of endothelin (40 and 400 pmol/kg, intravenous (i.v.), a novel vasoconstrictor, on haemodynamics were evaluated in normal dogs and dogs treated with hexamethonium.2. The lower dose of endothelin caused no significant changes in mean blood pressure (MBP), heart rate (HR), cardiac output (CO), or total peripheral resistance (TPR) in normal dogs. In dogs treated with hexamethonium MBP decreased transiently associated with decrease in TPR.3. In both dogs, the higher dose of endothelin caused MBP increase with CO increase in an early phase, and with TPR increase in a later phase. In normal dogs, the CO decreased 60 min after endothelin, but in dogs treated with hexamethonium the decrease in CO was not significant.4. Electrocardiograms showed ST changes and arrhythmias.5. Thus, endothelin has dual effects on both the vasculature and the heart, its effect depending on its dose and the time after its administration: initial vasodilation followed by prolonged vasoconstriction, and cardiostimulation followed by cardiosuppression. The cardiosuppression appears to be mediated in part by a neural mechanism.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01331.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. Little is known about the metabolism and the pharmacokinetics of dopamine (DA) in critically ill patients. To study the influence of the total administered DA dose on the disposition of free (i.e. unconjugated) and sulfoconjugated DA, plasma levels of free and sulfoconjugated DA were measured following infusion of 5 μg DA/kg per min for 0.5 and 3 h in six healthy volunteers and in eight critically ill patients receiving DA at the same infusion rate for 6.5 to 329 h.2. In patients and volunteers steady state concentrations of free DA showing fairly large inter‐individual variations (12.4–73.4 μg/L) were reached within 10 min of the beginning of the infusion.3. DA sulfate was generated immediately. In volunteers peak values of the sulfoconjugate were observed 15–60 min after the termination of the DA infusion. In patients steady state concentrations of conjugated DA (63–80 μg/L) were reached within 5–10 h of DA infusion.4. The initial half‐life (t1/2α), the terminal elimination half life (t1/2) and the distribution volume of free DA in the volunteers were significantly higher after 3 h of the DA infusion as compared to the shorter infusion. These parameters as well as the total plasma clearance of free DA were independent of the length of the DA infusion period in patients. The large distribution volumes of 19.8–75 L/kg indicate that DA has been taken up by peripheral tissues.5. Substantial inter‐individual variations in the patients' clearance of free DA (3.9–16.5 L/kg per h) may partly explain the variability in haemodynamic responses to DA infusion reported in clinical studies. No effects of DA on the systolic and diastolic blood pressures or the plasma concentrations of norepinephrine were found in the healthy subjects. The physiological significance of sulfated DA as a potential reserve pool for free DA has to

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01332.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. Adrenal TH activation was elicited in young rats (aged 4,6 and 14 days) by insulin hypoglycaemia. In the control rats, TH activation varied between 125 and 147% above basal values.2. Neonatal hypothyroidism induced by PTU treatment impaired TH activation. Compensatory treatment with T3to the PTU‐treated young rats led to a return to control activatio

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01333.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. Studies in the rat and the dog have shown that infusion of aldosterone for several weeks into the cerebral ventricles (ICV) can produce hypertension at doses that do not have an effect when infused systemically. We have previously shown that a high physiological dose of aldosterone infused intravenously at 10 μg/h in sheep produces an increase in blood pressure of 7 mmHg within 2 days.2. In this paper we report the effects of ICV infusion of aldosterone at 2 μg/h for 6 days in conscious sheep.3. Neither blood pressure nor heart rate were altered, and there were no consistent changes in any of the metabolic parameters measured.4. These results do not support a role for central effects of aldosterone in the hypertension produced by systemic infusion of the steroid in shee

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01334.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SUMMARY1. The effect of atrial natriuretic peptide (ANP) on α‐adrenoceptor agonist‐induced renin release was examined in the de‐ennervated kidney of the anaesthetized dog pretreated with propranolol (1 mg/kg, intravenous).2. Phenylephrine (50 ng/kg per min) infused into the renal artery increased the renal secretion rate of renin (RSR) without affecting systemic blood pressure or renal blood flow.3. Although basal RSR was unaffected, the phenylephrine‐induced increase in RSR was abolished during intrarenal arterial infusion of ANP (10 ng/kg per min).4. The results suggests that exogenously administered ANP could suppress α‐adrenoceptor‐mediated renin relea

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01335.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Herbal Remedies: Harmful and Beneficial Effects. By S. Talalaj and A. S. Czechowicz.Current Advances in ACE Inhibition. Edited by G. A. MacGregor and P. S. Sever.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01336.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1990.tb01337.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY