The mechanism of Ca2+i increase in blood cells of spontaneously hypertensive rats.
Cytoplasmic free calcium (Ca2+i) is increased in platelets and lymphocytes of spontaneously hypertensive rats (SHR) and, to a lesser extent, in essential hypertensive patients. In this study, a method was devised to evaluate cellular Ca fluxes and the cellular Ca buffering power by means of the intracellular Ca indicator Quin-2. Ca influx was measured under conditions of Ca-pump inhibition, either by vanadate or ATP depletion. Lymphocytes of 5-month-old SHR were compared with those of normotensive Wistar-Kyoto rats (WKY). In both strains, the Ca entry rate and the cellular buffering capacity were higher in vanadate-treated than in ATP-depleted cells. SH rats exhibited a higher Ca influx and a greater intracellular Ca buffering power when vanadate was used to stop the Ca pump; these differences, however, were abolished in ATP-depleted lymphocytes. It is suggested that Ca entry in lymphocytes is ATP-dependent. Accelerated Ca entry in SHR can account for the previously reported higher levels of intracellular free Ca.
D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D002118:Calcium / Q000097:blood*; D006973:Hypertension / Q000097:blood*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008433:Mathematics; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000255:Adenosine Triphosphate; D002118:Calcium