Kinetic characteristics of thrombin receptor-mediated responses in rat megakaryocytes.
Kinetic characteristics of thrombin receptor-mediated responses on rat megakaryocytes were examined by the use of the perforated patch clamp combined with the rapid drug exchange system termed the 'Y-tube method'. The application of thrombin evoked repetitive Ca(2+)-activated K+ current (IKCa) in a concentration-dependent manner. The characteristic features for thrombin-induced response compared with purinoceptor-induced response were the long latency, long washout time and fast desensitization. The similar IKCa as thrombin was induced by trypsin. Thrombin- and trypsin-induced IKCa were both inhibited by the protease inhibitor, SBTI, and the washout time for thrombin was markedly shortened (7.4 +/- 2.2 s) when thrombin was washed out by a solution containing soybean trypsin inhibitor. A synthetic thrombin receptor agonist peptide induced IKCa oscillation with shorter latency than thrombin.
Uneyama
C
C
Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
Uneyama
H
H
Narisawa
K
K
Takahashi
M
M
Akaike
N
N
D000818:Animals; D002118:Calcium / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D058914:Purinergic Antagonists; D051381:Rats; D011983:Receptors, Purinergic / Q000378:metabolism; D018179:Receptors, Thrombin / Q000187:drug effects / Q000378:metabolism*; D013268:Stimulation, Chemical; D013917:Thrombin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
D015221:Potassium Channels; D011480:Protease Inhibitors; D058914:Purinergic Antagonists; D011983:Receptors, Purinergic; D018179:Receptors, Thrombin; D014357:Trypsin; D013917:Thrombin; D002118:Calcium