Calcium antagonist isradipine improves abnormal endothelium-dependent vasodilation in never treated hypertensive patients.
OBJECTIVE
To examine whether middle (two months) and long-term (six months) isradipine sustained-release treatment improves endothelium-dependent vasodilation in never treated hypertensive patients.


METHODS
The responses of the forearm vasculature to acetylcholine (7.5, 15 and 30 micrograms/min) and sodium nitroprusside (0.8, 1.6, 3.2 micrograms/min) were evaluated in 12 normotensive controls (seven men and five women, aged 25 to 49 years), and in 12 hypertensives (eight men and four women, aged 20 to 47 years) at baseline and after two and six months of isradipine sustained-release treatment. Drugs were infused into the brachial artery, and forearm blood flow was measured by strain-gauge plethysmography.


RESULTS
At baseline, the response to acetylcholine was significantly lower in hypertensives vs controls: at the highest dose (30 micrograms/min), forearm blood flow was 28.6 +/- 2.4 ml/100 ml of tissue per min in the controls vs 8.9 +/- 1.0 ml/100 ml of tissue per min in hypertensive (p < 0.0001). Similarly, vascular resistance was significantly (p < 0.0001) higher in hypertensives: 4.8 +/- 0.5 units (controls) vs 15.1 +/- 1.7 units (hypertensives). After isradipine treatment, the forearm blood flow in hypertensive patients changed from 8.9 +/- 1.0 ml/100 ml of tissue per min to 16.0 +/- 1.2 ml/100 ml of tissue per min (two months; p < 0.0001) and 15.2 +/- 1.4 ml/100 ml of tissue per min (six months; p < 0.0001). Isradipine treatment did not modify the vasodilating effect of sodium nitroprusside.


CONCLUSIONS
Our data demonstrate for the first time that the calcium antagonist isradipine improves acetylcholine-induced vasodilation in hypertensives.
D000109:Acetylcholine; D000328:Adult; D000704:Analysis of Variance; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D016022:Case-Control Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D017275:Isradipine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009599:Nitroprusside; D012039:Regional Blood Flow / Q000187:drug effects; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents