H. Noguchi et al., ALPHA(1)-ADRENOCEPTOR SUBTYPE INVOLVED IN THE POSITIVE INOTROPIC RESPONSE TO PHENYLEPHRINE IN RAT ATRIA, European journal of pharmacology, 240(2-3), 1993, pp. 291-293
Phenylephrine produced positive inotropic responses in isolated rat ri
ght and left atria. The responses were competitively inhibited by alph
a1-adrenoceptor antagonists (prazosin, WB4101 and HV723) with relative
ly low affinities (pA2 values close to 8.0). Chloroethylclonidine had
no significant effect on the responses to phenylephrine. These results
suggest that the positive inotropic response to phenylephrine in rat
atria is mediated through alpha1-adrenoceptors which cannot be defined
by the alpha1A, alpha1B subclassification.