Blockade of different subtypes of α1-adrenoceptors produces opposite effect on heart chronotropy in newborn rats

Abstract

We compared the effects of blockade of α1A-, α1-, and α1D-subtypes of α1- adrenoceptors on the cardiac rhythm in newborn rats. Different responses of the heart were observed after blockade of several subtypes of α1- adrenoceptors. Administration of WB 4101, a selective blocker of α1A-adrenoceptors, increased heart rate, while blockade of α1AD-adrenoceptors with BMY 7378 decelerated of heart rhythm. Blockade of α1-adrenoceptors with chloroethylclonidine produced no significant effects on heart chronotropy. © 2012 Springer Science+Business Media New York.