Referenced in: none

Automatically associated channels: Kv1.2 , Kv1.4 , Slo1

Title: Modulation of K channels by coexpressed human alpha1C-adrenoceptor in Xenopus oocytes.

Authors: G N Tseng, J A Yao, J Tseng-Crank

Journal, date & volume: Am. J. Physiol., 1997 Mar , 272, H1275-86

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/9087602

Abstract
alpha1-Adrenoceptors participate in the regulation of inotropy and chronotropy in the heart. Modulation of cardiac K-channel function plays an important role in these alpha1-adrenergic functions. Studies of the mechanisms of K-channel modulation by alpha1-adrenoceptors are hampered by the coexistence of multiple receptor and channel subtypes in the heart. We therefore used a model system of coexpressing a specific receptor (human alpha1c-adrenoceptor) and a K-channel clone (hIsK, rKv1.2, or rKv1.4) in oocytes. alpha1c-Adrenoceptor stimulation caused a rapid upregulation of hIsK by elevating the intracellular Ca concentration. At least part of this effect was due to an activation of calmodulin and Ca/calmodulin-dependent protein kinase II. On the other hand, alpha1c-adrenoceptor stimulation caused a slow downregulation of rKv1.2 and rKvl.4 by activating protein kinase C. The differential modulation of K channels by alpha1c-adrenoceptors demonstrated in our experiments corroborates the complexity of alpha1-adrenergic functions in the heart. Our results indicate that the oocyte model system can be a useful approach in studying alpha1-adrenergic modulation of ion-channel function and signal transduction.