Basal and induced guanylate cyclase activity in patients with mild and moderate hypertension: Effect of long-term treatment with nebivolol

Basal and induced activity of soluble guanylate cyclase (CC) of platelets t aken from 10 patients (8 women and 2 men, mean age 55,2+/-4,3 years) with m ild and moderate essential hypertension was studied in vitro before and aft er 8 weeks of monotherapy with nebivolol (5-10 mg o.d.). Basal activity of GC before treatment was low (67,9+/-31,6 pmol/min per 1 mg of protein) comp ared with normal values (80-150 pmol/min per 1 mg of protein). After nebivo lol basal CC activity did not change while multiplication factor of stimula tion of CC activity by sodium nitroprusside decreased from 8,9+/-2,9 to 5,9 +/-1,8 (p<0,05), multiplication factor of stimulation by protoporphyrin IX increased from 3,8+/-1,4 to 6,0+/-2,1 (p<0,05). Reaction to other activator s (L-arginine, mercaptoethylguanidine disulfide and dinitrosyle complex of iron) remained unchanged. The results indicate that nebivolol affects endot helial function acting on the L-arginine (NO) guanylate cyclase system. Thi s effect apparently is responsible for vasodilating properties of nebivolol , Decreased activity of guanylate cyclase might be a marker of endothelial dysfunction in hypertension.