Calcium Antagonists Inhibit Elevated Potassium Efflux From Aorta of Aldosterone-Salt Hypertensive Rats

• Published in: Hypertension (Dallas, Tex. 1979) Tex. 1979), 1990-01, Vol.15 (1), p.78-83
• Main Authors: Smith, Jacquelyn M, Jones, Allan W
• Format: Article
• Language: English
• Subjects: Aldosterone; Animals; Antianginal agents. Coronary vasodilator agents; Aorta - metabolism; Aorta - physiopathology; Biological and medical sciences; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Cardiovascular system; Diltiazem - pharmacology; Hypertension - chemically induced; Hypertension - metabolism; Hypertension - physiopathology; In Vitro Techniques; Male; Medical sciences; Nisoldipine - pharmacology; Pharmacology. Drug treatments; Potassium - metabolism; Potassium Chloride - pharmacology; Rats; Rats, Inbred Strains; Sodium Chloride; Vasoconstriction - drug effects
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.HYP.15.1.78

The purpose of this study was to evaluate the effect of calcium antagonists on basal tension and the elevated 42K efflux in aorta from aldosterone-salt hypertensive rats. Diltiazem decreased the basal tension (2.0 ±0.4 g) as well as the phasic contractile activity and returned the elevated 42K efflux (0.018±0.002/min) toward control values (0.010±0.001/min, p < 0.001). The diltiazem median inhibitory concentration (IC50) for basal tension (0.04±0.02 juM), however, was sevenfold less than the IC50 for basal 42K efflux (0.22 ±0.08 /tM, p < 0.01). The basal 45Ca influx in aorta from aldosterone-salt hypertensive rats (120±4 /JJVI/1 cell H2O/min) was also decreased by diltiazem in a concentration-dependent manner, whereas the 45Ca influx in aorta from control-salt rats (135±3 /JM/1 cell H2O/min) was not altered. Similarly, the dihydropyridine nisoldipine eliminated the basal tension (2.7±0.5 g) and returned the elevated basal 42K efflux from the hypertensive aorta toward control levels (0.010 ±0.0003/min, p< 0.001). The nisoldipine IC50 for basal tension (0.016±0.01 nM) was 160-fold less than the IC50 for basal 42K efflux (1.8±1.2 nm,/;