Effect of protopine on cytosolic Ca2+ in rabbit platelets.
OBJECTIVE
To study the influence of protopine (Pro) on the cytoplasmic free Ca2+ concentration ([Ca2+]i) in rabbit platelets.


METHODS
Measurement of [Ca2+]i of platelets in vitro by Fura 2-AM fluorescence technique.


RESULTS
In the presence of CaCl2 1 mmol.L-1, Pro 10, 20, and 40 mumol.L-1 attenuated the rise in [Ca2+]i evoked by ADP from (420 +/- 57) to (320 +/- 26), (264 +/- 21), and (180 +/- 14) nmol.L-1, respectively, by arachidonic acid (AA) from (280 +/- 36) to (210 +/- 17), (184 +/- 21), and (143 +/- 16) nmol.L-1, respectively, and by platelet-activating factor (PAF) from (350 +/- 42) to (282 +/- 31), (223 +/- 30), and (165 +/- 15) nmol.L-1, respectively. In the presence of egtazic acid 1 mmol.L-1, Pro 10, 20, and 40 mumol.L-1 reduced the Ca2+ release induced by ADP, AA, and PAF, respectively. Pro 10, 20, and 40 mumol.L-1 also decreased ADP-, AA-, and PAF-induced Ca2+ influx.


CONCLUSIONS
Pro inhibited not only Ca2+ release but also the influx of Ca2+.
Shen
Z Q
ZQ
Yunnan Pharmacological Laboratories of Natural Products, Kunming Medical College, China.
Chen
Z H
ZH
Duan
L
L
D000244:Adenosine Diphosphate / Q000037:antagonists & inhibitors; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000037:antagonists & inhibitors; D053119:Benzophenanthridines; D001600:Berberine Alkaloids; D001693:Biological Transport, Active; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D005260:Female; D008297:Male; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011817:Rabbits
D000470:Alkaloids; D053119:Benzophenanthridines; D001600:Berberine Alkaloids; D010972:Platelet Activating Factor; D010975:Platelet Aggregation Inhibitors; D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D002118:Calcium; C009093:protopine