Negative chronotropic effect of cannabinoids and their water-soluble emulsion is related to activation of cardiac CB1 receptors.

Intravenous injection of cannabinoids dissolved in cremophore EL:ethanol:NaCl mixture and water-soluble emulsion of the same cannabinoids caused identical negative chronotropic effects in chloralose-narcotized rats. Selective CB1 and CB2 receptor antagonist HU-210 also induced a negative chronotropic effect in rats, while pre-injection of CB1 receptor antagonist SR 141716A completely abolished this effect of HU-210. Selective CB2 receptor antagonist SR 144528 had no effect on HU-210-induced bradycardia.

G protein-coupled receptor kinase 6 (GRK6) selectively regulates endogenous secretin receptor responsiveness in NG108-15 cells.

1. To determine the role of G protein-coupled receptor kinases (GRKs) in the regulation of endogenous secretin receptor responsiveness, we have transiently overexpressed both wild-type (WT) and dominant negative mutant (DNM) GRKs in NG108-15 mouse neuroblastoma x rat glioma hybrid cells and investigated the effects of this on agonist-stimulated adenylyl cyclase activity. 2.

Second messenger-dependent protein kinases and protein synthesis regulate endogenous secretin receptor responsiveness.

1. The present study investigated the role of second messenger-dependent protein kinase A (PKA) and C (PKC) in the regulation of endogenous secretin receptor responsiveness in NG108-15 mouse neuroblastomaxrat glioma hybrid cells. 2.