<原著>SHRSPの血小板凝集能変化, とくに加齢および高血圧との関連性について

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It has been reported that compared with WKY platelets the platelets of SHR and/or SHRSP showed the lower aggregation activities which would be due to the extreme conse quences of hypertension developed with aging. The present study was conducted to reexamine the platelet aggregation activity with several aggregation reagents of different types. The agematched male SHRSP and normotensive WKY of 2 to 12 months old, being bred in our laboratory, were subjected to this experiment. Platelet rich plasma (PRP) and washed platelet suspended in the Hepes buffer containing 1 mM CaCl_2,each consisting of 2.5×10^5 cells/μl×200μl, were used for the measurement of the platelet aggregation activity using an aggregometer (NKK hema tracer 1). Maximal light transmittance (660nm) at 5min after the addition of auggregation reagents such as ADP (1,3 and 10μM), collagen (10,30 and 50μg/ml), thrombin (0.1,0.3 and 1.0U/ml), arachidonic acid (0.1,0.3 and 1.0mM), A23187 (1,3and 10μM), and TPA (1,3 and 10nM) indicated the aggregation activity, and the values obtained were compared between the two rat groups. ADP-induced aggregation activities in WKY PRP were not changed from 2 to 12 months old, being sustained during this period. On the other hand, these activities in the SHRSP platelet rich plasma tended to be less than those in WKY PRP even at 2 months old, and significantly lower values were obtained with the SHRSP which was older than 4 months of age. The similar results were obtained with the washed platelet samples of SHRSP and WKY. The collagen-induced aggregation activities also showed the same results with the ADP-induced ones. Thrombin-induced aggregation activities of washed platelets from the rats of 2 to 10 months old were significantly less in SHRSP than in WKY. Arachidonic acid, A23187 and TPA-induced aggregation activities of washed platelets showed no significant difference between the SHRSP and WKY being from 2 to 10 months of age. From these results, the following conclusions may be drawn. 1) Intracellular aggregation pathways involved in arachidonic acid metabolism, C-kinase system and free calcium ion utilization were rigid both in SHRSP and WKY. 2) Both phospholipase A_2 and C activities might be almost unchanged. 3) Receptor mediated aggregation assigned to SHRSP platelet even at the younger ages may occur to the lesser extent compared with WKY platelet aggregation. Taken these together, it has been corroborated that on the plasma membrane levels some unknown defects present in SHRSP platelet may interfere with the receptor mediated signals on the way to the second intracellular messengers, which may play etiologic roles in the developing hypertensive state.
近畿大学の論文
1989-03-25

著者

口分田真
近畿大学医学部薬理学教室

<原著>SHRSPの血小板凝集能変化, とくに加齢および高血圧との関連性について

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