Abstract
Postsynaptic alpha adrenoceptors have been characterized in rat superior mesenteric artery and branches of canine mesenteric artery. l-Phenylephrine, naphazoline and colonidine were used as agonists and prazosin and yohimbine were used as antagonists. The pA2 values for prazosin and yohimbine were determined against these agonists in canine and rat mesenteric arteries. The pA2 values for either prazosin or yohimbine were similar when l-phenylephrine and naphazoline were used as the agonists. The slope of the Schild plot was less than unity for prazosin and yohimbine acting as antagonists to l-phenylephrine in canine mesenteric artery whereas in the rat mesenteric artery, the slopes obtained for either phenylephrine or naphazoline against the antagonists were not significantly different from unity. In rat mesenteric artery, the pA2 value for yohimbine against clonidine was not statistically different from values obtained with the other agonists; however, in the presence of prazosin the dose-response curve to clonidine was biphasic, suggesting that the action of clonidine is mediated through two distinct sites to which prazosin has different affinities. However, these results do not provide definitive support for the concept of functionally independent subtypes of postsynaptic alpha adrenoceptors in rat and canine mesenteric artery.
| Original language | English |
|---|---|
| Pages (from-to) | 831-838 |
| Number of pages | 8 |
| Journal | Journal of Pharmacology and Experimental Therapeutics |
| Volume | 229 |
| Issue number | 3 |
| State | Published - 1984 |
| Externally published | Yes |
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All Science Journal Classification (ASJC) codes
- Pharmacology
Cite this
Pharmacological characterization of the postsynaptic alpha adrenoceptors in vascular smooth muscle from canine and rat mesenteric vascular beds. / Agrawal, Devendra K.; Triggle, C. R.; Daniel, E. E.
In: Journal of Pharmacology and Experimental Therapeutics, Vol. 229, No. 3, 1984, p. 831-838.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Pharmacological characterization of the postsynaptic alpha adrenoceptors in vascular smooth muscle from canine and rat mesenteric vascular beds
AU - Agrawal, Devendra K.
AU - Triggle, C. R.
AU - Daniel, E. E.
PY - 1984
Y1 - 1984
N2 - Postsynaptic alpha adrenoceptors have been characterized in rat superior mesenteric artery and branches of canine mesenteric artery. l-Phenylephrine, naphazoline and colonidine were used as agonists and prazosin and yohimbine were used as antagonists. The pA2 values for prazosin and yohimbine were determined against these agonists in canine and rat mesenteric arteries. The pA2 values for either prazosin or yohimbine were similar when l-phenylephrine and naphazoline were used as the agonists. The slope of the Schild plot was less than unity for prazosin and yohimbine acting as antagonists to l-phenylephrine in canine mesenteric artery whereas in the rat mesenteric artery, the slopes obtained for either phenylephrine or naphazoline against the antagonists were not significantly different from unity. In rat mesenteric artery, the pA2 value for yohimbine against clonidine was not statistically different from values obtained with the other agonists; however, in the presence of prazosin the dose-response curve to clonidine was biphasic, suggesting that the action of clonidine is mediated through two distinct sites to which prazosin has different affinities. However, these results do not provide definitive support for the concept of functionally independent subtypes of postsynaptic alpha adrenoceptors in rat and canine mesenteric artery.
AB - Postsynaptic alpha adrenoceptors have been characterized in rat superior mesenteric artery and branches of canine mesenteric artery. l-Phenylephrine, naphazoline and colonidine were used as agonists and prazosin and yohimbine were used as antagonists. The pA2 values for prazosin and yohimbine were determined against these agonists in canine and rat mesenteric arteries. The pA2 values for either prazosin or yohimbine were similar when l-phenylephrine and naphazoline were used as the agonists. The slope of the Schild plot was less than unity for prazosin and yohimbine acting as antagonists to l-phenylephrine in canine mesenteric artery whereas in the rat mesenteric artery, the slopes obtained for either phenylephrine or naphazoline against the antagonists were not significantly different from unity. In rat mesenteric artery, the pA2 value for yohimbine against clonidine was not statistically different from values obtained with the other agonists; however, in the presence of prazosin the dose-response curve to clonidine was biphasic, suggesting that the action of clonidine is mediated through two distinct sites to which prazosin has different affinities. However, these results do not provide definitive support for the concept of functionally independent subtypes of postsynaptic alpha adrenoceptors in rat and canine mesenteric artery.
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M3 - Article
VL - 229
SP - 831
EP - 838
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
SN - 0022-3565
IS - 3
ER -