Changes in free calcium concentrations in platelets of SHRSP and WKY: its relationship to ATP releasing potencies and platelet aggregation activities upon stimulation of several reagents.
To clarify the relationships between free calcium levels, ATP release and aggregation potencies of SHRSP platelets, we examined the platelets from 9-month-old SHRSP and WKY using fura-2AM and luciferine-luciferase. In the absence of extracellular Ca2+, each reagent elevated the free calcium level to the same extent in the samples of both SHRSP and WKY. With regard to ATP release, thrombin and collagen less potentiated the platelet action in SHRSP than WKY, and ATP release was not affected by extracellular Ca2+. Collagen and ADP induced aggregations showed lower activities in SHRSP than WKY. TPA caused higher Ca2+ influx and aggregation activity in SHRSP than WKY in the presence of extracellular Ca2+. These results indicate that Ca2+ release must be followed by ATP release, and ATP release may be less potentiated, while thrombin and TPA induced aggregation is likely to be stimulated in SHRSP platelets, because protein kinase C activity in SHRSP platelets appears to be high.
Higashino
H
H
Department of Pharmacology, Kinki University School of Medicine, Osaka-Sayama, Japan.
Suzuki
A
A
D000255:Adenosine Triphosphate / Q000097:blood*; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D002561:Cerebrovascular Disorders / Q000235:genetics*; D004198:Disease Susceptibility; D006973:Hypertension / Q000097:blood* / Q000235:genetics; D007202:Indicators and Reagents; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013045:Species Specificity
D007202:Indicators and Reagents; D000255:Adenosine Triphosphate; D002118:Calcium