Kawai Y, Ohhashi T
1st Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
J Pharmacol Exp Ther. 1990 Mar;252(3):1234-9.
The effect of aging on responses of vascular smooth muscles to atrial natriuretic peptide (ANP) and other vasodilator substances was investigated in isolated rat aortae, rat renal arteries and monkey renal arteries which were precontracted with norepinephrine. There was no significant difference in the ANP-induced maximum relaxation between young and old rat aortae. However, the concentration of agonists causing a 50% relaxation (ED50) value for the old rats was 7.3 times greater than that for the young ones. In rat and monkey renal arteries, the ED50 ratios were 6.2 and 3.8, respectively. The relaxant responses of the rat aortae to isoproterenol and acetylcholine also decreased with increasing age. The ED50 ratios for isoproterenol and acetylcholine were more than 40 and 17, respectively. The maximum relaxation induced by 10(-5) M isoproterenol also decreased significantly in the aortae from the older rats. On the other hand, the ED50 for nitroprusside, nifedipine- and potassium-induced relaxation was not affected by increasing age. These results suggest that ANP-induced relaxation of vascular smooth muscles is reduced with increasing age in rat aortae, rat renal arteries and monkey renal arteries. The mechanisms by which the ANP-induced relaxation decreased in association with the aging process may be quite different from those in acetylcholine-induced and beta adrenoceptor-induced relaxation.
在分离的大鼠主动脉、大鼠肾动脉和猴肾动脉中，研究了衰老对血管平滑肌对心房利钠肽（ANP）和其他血管舒张物质反应的影响，这些血管预先用去甲肾上腺素进行了收缩。年轻和老年大鼠主动脉对ANP诱导的最大舒张反应无显著差异。然而，老年大鼠引起50%舒张（ED50）值的激动剂浓度是年轻大鼠的7.3倍。在大鼠和猴肾动脉中，ED50比值分别为6.2和3.8。大鼠主动脉对异丙肾上腺素和乙酰胆碱的舒张反应也随着年龄的增加而降低。异丙肾上腺素和乙酰胆碱的ED50比值分别超过40和17。老年大鼠主动脉中10^(-5)M异丙肾上腺素诱导的最大舒张也显著降低。另一方面，硝普钠、硝苯地平和钾诱导的舒张的ED50不受年龄增加的影响。这些结果表明，在大鼠主动脉、大鼠肾动脉和猴肾动脉中，随着年龄的增加，ANP诱导的血管平滑肌舒张减少。与衰老过程相关的ANP诱导舒张减少的机制可能与乙酰胆碱诱导和β肾上腺素能受体诱导舒张的机制有很大不同。
