| Abstract: | Cytosolic free calcium concentration ([Ca2+]i) in platelets has been reported to be elevated in human essential hypertension, to be positively correlated with blood pressure and to decrease with blood pressure reduction. However, some groups have been unable to confirm these findings in either humans or hypertensive rats. We have examined the relationship between platelet [Ca2+]i and blood pressure in the perinephritis model of hypertension in the rabbit. In addition, the effects of both acute and chronic treatment with verapamil or prazosin were studied. Mean arterial pressure, heart rate and platelet [Ca2+]i were measured before and after treatment. Platelet [Ca2+]i was measured by the Quin 2 fluorescence technique. Platelet [Ca2+]i was similar for the normotensive and hypertensive rabbits, and no correlation between platelet [Ca2+]i and blood pressure was observed. None of the antihypertensive treatments produced a lowering of platelet [Ca2+]i. Therefore we conclude that platelet [Ca2+]i is unlikely to be a universally useful index of [Ca2+]i in vascular smooth muscle of resistance vessels. |
