Increased Internal Calcium Mobilization in Platelets of Patients with Chronic Renal Failure

Summary

Platelet free calcium concentrations ([Ca²⁺]i) were measured with Fura-2 to elucidate the intracellular calcium kinetics in patients with renal disease. There were no significant differences of the resting [Ca²⁺]i among the control subjects (C) (n = 12), patients with chronic glomerulonephritis (CGN) (n = 8), and patients with chronic renal failure (CRF) (n = 12). In all groups, platelets [Ca²⁺]i were significantly increased by agonists (thrombin, adenosine diphosphate) compared with their respective basal level. Thrombin-induced [Ca²⁺]i rise was significantly higher in CRF (840±265 nM) than in C (600±163) and CGN (562±137). Also adenosine diphosphate elicited similar responses. In the presence of calcium chelator in the incubation buffer, the elevation of [Ca²⁺]i after thrombin stimulation was statistically higher in CRF (469 ±85 nM) than in C (275±60) and CGN (301±41). These findings suggest that platelets of CRF were capable of increasing [Ca²⁺]i in response to agonists, through further mobilization of calcium from the intracellular pool rather than the elevation of transmembrane calcium influx.

Key words

Platelet Free Calcium - Thrombin - Adenosine Diphosphate - Chronic Renal Failure - Parathyroid Hormone