Effects of nitrendipine and tiapamil on 45Ca2+ influx and on platelet aggregation.
The effects of the dihydropyridine derivative nitrendipine and of the phenylalkylamine derivative tiapamil on 45Ca2+ influx was determined in platelets in vitro and on platelet aggregation ex vivo. Thrombin-stimulated 45Ca2+ influx was inhibited by 10 mumol/l nitrendipine and 100 mumol/l tiapamil. ADP- and adrenaline-induced platelet aggregation were inhibited in normotensive volunteers following short-term administration of nitrendipine (20 mg b.i.d.) but not after tiapamil (225 mg t.i.d.). Therefore, mechanisms other than the inhibition of Ca2+ influx should be considered to be responsible for inhibition of platelet aggregation by nitrendipine ex vivo.
Kribben
A
A
Department of Internal Medicine, Klinikum Steglitz, Freie Universität Berlin, F.R.G.
Fritschka
E
E
Senger
D
D
Sibold
M
M
Distler
A
A
Philipp
T
T
D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009568:Nitrendipine / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D011437:Propylamines / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology; D013976:Tiapamil Hydrochloride
D002121:Calcium Channel Blockers; D011437:Propylamines; D009568:Nitrendipine; D013917:Thrombin; D002118:Calcium; D013976:Tiapamil Hydrochloride