Alpha-adrenoceptors in the rabbit intestine and aorta
Jagadeesh, G.; Das, P.K.
Indian Journal of Medical Research 74: 586-594
1981
ISSN/ISBN: 0019-5340 PMID: 6279491 Document Number: 179828
In a comparative study of the .alpha.-adrenoceptors of rabbit jejunum and aorta, the 3 agonists, epinephrine (E), norepinephrine (NE) and phenylephrine (PE) showed similar intrinsic activities and order of potency (E > NE > PE) in both tissues. The pD2 [log molar ED50] values of the 3 agonists were slightly higher in the aorta than in the intestine. The mean relative potency ratios of the 3 agonists (E : NE : PE) in the intestine changed from 1.36 : 1.00 : 0.25 to 1.96 : 1.00 : 0.20 by bunolol pretreatment. Bunolol treatment did not affect the mean potency ratios in the aorta. The pA2 values of phentolamine against the 3 agonists were not significantly different in both the tissues. The slope of phentolamine-PE interaction curve in intestine was near -1.0, and was similar to that of aorta. Bunolol pretreatment significantly altered the slope and pA2 values of phentolamine against E in intestine but not in aorta. The differences in the actions of E and NE and their modifications by bunolol pretreatment in intestine were possibly due to their actions on .alpha.-and .beta.-adrenoceptors. The .alpha.-adrenoceptors of rabbit intestine evidently are not different from those of the aorta.