Altered agonist-induced Ca2+ mobilization in aortic smooth muscle cells from cardiomyopathic hamsters.
We compared the responses to the Ca(2+)-mobilizing effects of norepinephrine (NE), endothelin-1 (ET), and arginine vasopressin (AVP) of primary cultures of vascular smooth muscle cells (VSMCs) from aortas of young (30-40 days old) cardiomyopathic (Bio 14.6 strain) and age-matched control hamsters. In Bio 14.6 VSMCs, saturating concentrations of NE and ET elicited increases in the intracellular Ca2+ concentration ([Ca2+]i), which reached approximately 50 and 62% of those in control VSMCs. AVP elicited a significant increase in [Ca2+]i only in Bio 14.6 VSMCs. In contrast, 10 microM ionomycin induced similar Ca2+ responses in both types of cells in the absence of extracellular Ca2+. Ligand binding assay revealed that maximal binding values for alpha 1-adrenergic antagonists and ET in Bio 14.6 VSMCs were 59-64 and 85% of those in control VSMCs. Thus VSMCs from aortas of Bio 14.6 hamsters had reduced reactivity to NE and ET but increased response to AVP. The reduced Ca2+ response of Bio 14.6 VSMCs to NE appeared to be due mainly to a decrease in the receptor number.
Tawada-Iwata
Y
Y
Department of Molecular Physiology, National Cardiovascular Center Research Institute, Osaka, Japan.
Furukawa
K
K
Ogurusu
T
T
Nakamura
H
H
Shigekawa
M
M
D000818:Animals; D001011:Aorta / Q000378:metabolism* / Q000473:pathology; D001127:Arginine Vasopressin / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D009202:Cardiomyopathies / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D016232:Endothelins / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D009638:Norepinephrine / Q000494:pharmacology
D016232:Endothelins; D001127:Arginine Vasopressin; D002118:Calcium; D009638:Norepinephrine