RT Journal Article
SR Electronic
T1 Correlation between phosphatidylinositol labeling and contraction in rabbit aorta: effect of alpha-1 adrenergic activation.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 258
OP 261
VO 222
IS 1
A1 R Villalobos-Molina
A1 M Uc
A1 E Hong
A1 J A García-Sáinz
YR 1982
UL http://jpet.aspetjournals.org/content/222/1/258.abstract
AB Activation of rabbit aortic strips with alpha adrenergic agonists increased the labeling (with [32P]Pi) of phosphatidylinositol (PI) and phosphatidic acid and contracted the vascular preparations in dose-related fashion. Epinephrine, norepinephrine and methoxamine produced maximal effects, whereas clonidine behaved as partial agonist and B-HT 933 (2-amino-6-ethyl-4,5,7,8-tetrahydro-6H-oxazole-[5,4-d] azepin dihydrochloride) was almost without activity in the two experimental models used. Phenylephrine was a full agonist in producing contraction, but failed to elicit the maximal increase in PI labeling. The EC50 values to produce contraction of aortic strips were lower for all agonists than those required to increase the incorporation of radioactive phosphate into PI, but there was a good correlation between the two sets of data. The increased PI labeling and contraction of aortic strips induced by epinephrine were antagonized by prazosin and yohimbine in dose-related fashion, but the first alpha blocker was about three orders of magnitude more potent than the second in antagonizing the two effects. The present results indicate that both stimulation of PI labeling and contraction are mediated through activation of alpha-1 adrenoceptors in rabbit aorta.