Hyperreactivity of Platelets from Spontaneously Hypertensive Rats
نویسنده
چکیده
Thrombin-induced serotonin secretion from platelets from age-matched spontaneously hypertensive rats (SHR) and control Wistar-Kyoto rats (WKY) was compared in the presence of different Ca+ and Mg concentrations. Platelets from SHR were more reactive than those of WKY, and the difference was more marked in 11-week-old than in younger rats. The responses to three concentrations of extracellular Ca and one extracellular Mg concentration of 1(H M were compared. A high external Ca concentration (2 x 10-3 M) increased secretion in platelets of both strains without suppressing the difference between them. Platelets from SHR were more sensitive than those from WKY to a low external Ca concentration (2 x 1(H> M). Platelet secretion which is independent of external Ca concentration was higher in platelets from SHR than in those from WKY. External Mg exerted an inhibitory effect on serotonin secretion in both types of platelets, but platelets from SHR were less sensitive to Mg than were those from WKY. This inhibitory effect appeared to be complex. It could be observed in the absence of external Ca, and in this case, the difference in reactivity between platelets SHR and WKY depended on the external Mg concentration (up to 2 x 10-3 M). Furthermore, a Mg -induced antagonism of the stimulatory effect of external Ca concentration appeared at higher concentrations of extracellular Mg and was more potent in platelets from WKY than in those from SHR. These results suggest that the hyperreactivity of platelets from SHR is related to an increased sensitivity to external Ca and a decreased sensitivity to external Mg and that an anomaly in the cellular response to physiological concentrations of Mg may be important in the pathophysiology of essential hypertension. (Hypertension 8: 694-699, 1986)
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تاریخ انتشار 2005