| Autor: |
Antonaccio, M J, Normandin, D, Serafino, R, Moreland, S |
| Zdroj: |
The Journal of Pharmacology and Experimental Therapeutics; July 1993, Vol. 266 Issue: 1 p125-132, 8p |
| Abstrakt: |
The role of thrombin receptor activation in isolated rat aortic rings was examined. The human thrombin receptor activating peptides (TRAPs) SFLLRNPNDKYEPF (TRAP1-14), SFLLRNP (TRAP1-7) and rat TRAP1-7 (SFFLRNP) all caused concentration-related (0.1-100 microM) contractions of endothelium-rubbed rat aortic rings. Reversal of the first two amino acids in TRAP1-14 ("reverse TRAP1-14") resulted in total loss of activity. The contractions caused by the TRAPs were reduced substantially in endothelium-intact rings due to endothelium-derived relaxing factor release because the reduced contractions were reversed by N omega-nitro-L-arginine or methylene blue. Contractions were significantly but only slightly enhanced by alpha receptor blockade and were not affected by thromboxane- or endothelin-receptor blockade or by cyclooxygenase inhibition. TRAP1-7 had no effect on contractile responses to norepinephrine, serotonin, angiotensin II or endothelin-1; however, pretreatment with nifedipine or removal of extracellular Ca++ markedly inhibited the contraction. Neither human nor rat alpha-thrombin had any contractile effect on rat aortic rings. In cultured rat aortic smooth muscle cells, alpha-thrombin (EC50 = 1.9 +/- 0.7 nM), TRAP1-14 (EC50 = 30 +/- 4 microM) and TRAP1-7 (EC50 = 20 +/- 9 microM) caused concentration-dependent increases in intracellular calcium [Ca++]i, whereas reverse TRAP1-14 was ineffective. The effect of thrombin on [Ca++]i was abolished by the thrombin inhibitor MD-805, whereas the responses to TRAP were unaffected.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: |
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