Plasma digitalis-like activity and cytosolic Ca2+ in essential hypertension.
Digitalis compounds are known to increase Ca2+ influx in various cells. As platelet cytosolic free [Ca2+] and plasma digitalis-like activity have been reported independently to be higher in some untreated hypertensive patients than in normotensive subjects, we have investigated a possible relationship between these two parameters. Platelet cytosolic free [Ca2+], determined using Quin-2, the capacity of plasma extracts to inhibit renal Na+, K(+)-ATPase activity and ouabain binding on human erythrocytes were measured in parallel in 25 untreated hypertensive patients and 11 normotensive subjects. Enhanced values for all 3 parameters were observed in the same hypertensive patient. Platelet cytosolic free [Ca2+] was positively correlated to the plasma digitalis-like activity, which was evaluated by the inhibition of Na+, K(+)-ATPase activity and ouabain binding (r = 0.430, P = .010 and r = 0.448, P = .006, respectively). These relationships were independent of age and blood pressure. These results indicate that endogenous digitalis-like compounds may participate in the control of cytosolic free [Ca2+], in agreement with their proposed hypertensive role.
Le Quan Sang
K H
KH
Department of Pharmacology, Faculty of Medècine Necker-Enfants Malades, Paris, France.
Pernollet
M G
MG
Meyer
P
P
Devynck
M A
MA
D000293:Adolescent; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D002298:Cardenolides; D003600:Cytosol; D004077:Digoxin; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010042:Ouabain / Q000097:blood; D012503:Saponins; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000097:blood
D001798:Blood Proteins; D002298:Cardenolides; D012503:Saponins; C034504:digoxin-like factors; D010042:Ouabain; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium