1978 年 19 巻 4 号 p. 642-643
The C-A curves of NA in SHRSP and WKR were modified by aging but those of ACh were not. These results suggest that the modification of receptors by aging may be produced in only adrenaline receptor and the difference observed by the investiagators on the responses to sympathomimetics may be due to the age of rats used.It is clarified that the shift to the right of C-A curve means the decreased affinity (A) and the shift to the downward means the decreased intrinsic activity (IA). A and IA in adrenaline receptor at the ages of 3 and 11M of SHRSP were decreased compared to those of WKR at the same ages. There are some reports that the catecholamine contents in blood of SHRSP was high at the age of 1 to 2M. It may be thought that the increased catechomaine contents in blood influenced on adrenaline receptor and inhibited A and IA, by desensitization and/or the other mechanisms. &-stimulant, oricprenaline showed weaker inhibition against the contractions by the agonists in SHRSP than those in WKR, but dibutyryl C. AMP showed almost the same degree of inhibitory effect on the contractions by the agonists in SHRSP and WKR. These results suggest that the productive activity of C. AMP by &-stimulant may be lower in SHRSP compared to that in WKR. It seems to be coincidance with the previous reports that adenylcyclase activity in SHR-SP was lower than in normotensive rats.Ca antagonist, diltiazem showed the preferential antagonism against the cont-raction by K in SHRSP. It is clarified that the K-induced contraction is induced by only Ca influx, and thus it is thought that Ca influx may be accelerated in SHRSP. The decreased C. AMP productive activity and the increased Ca influx may be the factors of hypertension in SHRSP.
