[Essential hypertension and platelet cytosolic concentrations of H(+) and Ca2(+)].
Essential hypertension is associated with various cell abnormalities, including alterations in the metabolism of intracellular messengers, such as cytosolic free Ca2+ and cyclic AMP or IP3. Intracellular pH is implicated in the regulation of number vital functions, including cell metabolism, division and response to various stimuli. We have measured cytosolic H+ concentration ([H+]i) in human platelets and investigated a possible relationship with free Ca2+ concentrations ([Ca2+]i) in hypertensive patients. [H+]i was determined with the pH sensitive fluorescent probe BCECF in platelets from 15 normotensive subjects and 15 patients with mild to moderate essential hypertension, free from medication, il any, for at least two weeks. Donor characteristics are indicated in the table. (table; see text) [H+] cytosolic from hypertensive patients was significantly lowered by 21 p. 100 compared to normotensive values (table). Cytosolic free Ca2+ concentrations, measured with the Ca2+ fluorescent probe Fura2, were significantly increased by 19 p. 100 in platelets from hypertensive patients when compared to those of normotensive donors. Taken all together, [H+]i and [Ca2+]i varied inversely (r = -0.421, p = 0.02) in these thirty donors and tends to be correlated in the essential hypertensive patients (r = 0.490, p = 0.06). This correlation remained significant at constant age systolic and diastolic blood pressures. The simultaneous rise in [H+]i and [Ca2+]i in platelets from essential hypertensive patients are compatible with their observed enhanced sensitivity to several aggregating agents. This alkalinisation, if present in the vascular smooth muscle cells, may also reflect facilitated cell proliferation and increased sensitivity to stimulating agents, two parameters implicated in the rise of arterial blood pressure.
Astarie
C
C
INSERM U7/UA 318 CNRS, département de pharmacologie, hôpital Necker, Paris.
Levenson
J
J
Simon
A
A
Meyer
P
P
Devynck
M A
MA
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006973:Hypertension / Q000097:blood*; D008297:Male; D008875:Middle Aged
D002118:Calcium
Hypertension essentielle et concentrations plaquettaires cytosoliques d'ions H+ et Ca2+.