Abstract
The pA2 of phentolamine in cat spleen is significantly different from that reported for phentolamine in strips of rabbit aorta. The present report gives a detailed analysis of the alpha adrenergic receptors in the aorta and spleen of the rabbit. The dissociation constant (KB) of phentolamine has been found to be approximately 2 to 5 times greater in the spleen than the aorta (significantly different, P < .05). The KB values of azapetine and yohimbine were also significantly different in these two tissues. The dissociation constants of several agonists (KA) were found to differ by as much as 10-fold in these two tissues. The efficacy spleen/efficacy aorta ranged from 0.26 to 2.6 (excluding tyramine which had no agonist activity in spleen strips from reserpine-pretreated rabbits). The data indicate the possibility that alpha adrenergic receptors in these two tissues differ from each other.
Footnotes
- Received July 12, 1971.
- Accepted October 13, 1971.
- © 1972 by The Williams & Wilkins Co.
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