The severity and pattern of coronary artery disease in patients referred for investigation of the disease was compared between Asian and white patients living in Birmingham, matched for age, sex, blood pressure, and duration of symptoms, to investigate the clinical impression that Asians have worse, in particular worse distal, coronary artery disease than whites. Risk factors and outcome were also examined. The coronary angiograms of 34 Asians were compared blindly and repeatedly with those of 68 whites by two independent observers. Coronary artery disease was found to be quantitatively more severe in Asians, but the distribution of the disease was the same. Some risk factors were significantly different: fewer Asians were smokers; fasting cholesterol concentrations were higher in whites; and whites were heavier, with a larger body surface area. Follow up data showed that more Asians were refused coronary artery bypass surgery because of the severity of their disease.

Eight normotensive male subjects were infused with angiotensin II or phenylephrine in a single blind fashion. Measurements were made of blood pressure and pulse interval every 3 min, and blood drawn for plasma catecholamines at the beginning and end of the infusion. Phenylephrine produced a rise in blood pressure which was associated with a bradycardia in all subjects. A statistically significant relationship between blood pressure and pulse interval was observed in all subjects. In contrast, angiotensin II infusion produced an equal pressor response, but the change in pulse interval was statistically significantly less than that seen following phenylephrine infusion. In seven of eight subjects no significant relationship was observed between blood pressure and pulse interval. Plasma noradrenaline levels were similar before each pressor infusion and were unchanged during each infusion. These observations are consistent with central inhibition of the baroreceptor heart rate reflex by angiotensin II in man.

SUMMARY The influence of acute and chronic treatment with felodipine on ambulatory intraarterial blood pressure, certain cardiac reflexes, and plasma renin activity was studied in nine patients with essential hypertension. Acute oral administration of the drug caused a significant reduction in blood pressure associated with an increase in heart rate mediated by the sinoaortic baroreceptorheart rate reflex. After 1 week of treatment reflex resetting had occurred, returning heart rate to normal despite continuing blood pressure reduction. This effect was maintained throughout 6 weeks of treatment. Withdrawal of treatment was followed by return of the blood pressure to control levels associated with significant bradycardia caused by reflex reactivation at its reset level. No change was observed in response to tilting or Valsalva's maneuver or in plasma renin activity. Ambulatory intraarterial data suggested that the clinically useful antihypertensive action of felodipine persists for 9 hours. (Hypertension 8: 1172(Hypertension 8: -1178(Hypertension 8: , 1986 KEY WORDS • felodipine • sinoaortic baroreceptor reflex • calcium antagonist • hypertension • vasodilator T HE antihypertensive action of many vasodilating drugs is antagonized by an increase in sympathetic nervous system activity, which increases heart rate and cardiac output and stimulates the renin-angiotensin system. We have shown that chronic treatment with the calcium antagonist and vasodilator nifedipine 1 and with the related drug nicardipine 2 can reset the sinoaortic baroreceptor heart rate (SAB-HR) reflex and increase its sensitivity, allowing sustained blood pressure reduction without persistent tachycardia.Felodipine is a new dihydropyridine calcium channel entry blocker that is similar to nifedipine. It reduces blood pressure principally by its action on vascular smooth muscle 3 with minimal effects on myocardial contractility and conduction. 4 ' 5 Acute administration of this drug reduces peripheral vascular resistance and blood pressure with an increase in heart rate and cardiac output. 6 The aims of this study were 1) to examine the acute and chronic effects of felodipine on ambulatory intraarterial blood pressure, SAB-HR reflex sensitivity, Received April 2, 1986; accepted July 23, 1986. and set point; the responses to tilt and Valsalva's maneuver; and the renin-angiotensin system in hypertensive humans, and 2) to investigate the time course of SAB-HR reflex resetting.Patients and Methods Nine patients (5 men, 4 women) with an age range of 35 to 59 years (mean, 46.3 years) and with an average outpatient casual blood pressure of (mean ±

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Felodipine, a selective arteriolar dilator, was given to 13 hypertensive patients to assess its hypotensive effects and duration of action. Nine patients were treated with 5 mg three times a day and 4 with 10 mg three times a day. Mean blood pressures fell with both treatment regimens: 5 mg placebo 170/103 mmHg; 5 mg felodipine 148/91 mmHg; 10 mg placebo 154/93 mmHg; 10 mg felodipine 137/82 mmHg. Heart rates increased as blood pressures fell with both treatments. However, in the patients given 5 mg three times a day this effect was less noticeable after successive doses. Plasma concentrations of noradrenaline, both resting and tilted, increased after felodipine. There was a negative correlation between the fall in blood pressure and the increase in noradrenaline, suggesting that those patients with good baroreceptor reflexes were better able to counteract the effects of vasodilatation. Four of the nine patients treated with 5 mg felodipine three times a day experienced mild and transient adverse effects. Of the four patients treated with 10 mg three times a day, three experienced moderate to severe headache, and for this reason recruitment into this group was stopped. Felodipine at a divided daily dose of 15 mg effectively lowered blood pressure.