Conserved smooth muscle contractility and blood pressure increase in response to high-salt diet in mice lacking the beta3 subunit of the voltage-dependent calcium channel.
Voltage-dependent calcium channels are crucially important for calcium influx and the following smooth muscle contraction. Beta subunits of these channels are known to modify calcium currents through pore-forming alpha subunits. Among the four reported independent beta subunits, the beta3 subunit is expressed in smooth muscle cells and thought to compose L-type calcium channels in the tissue. To determine the role of the beta3 subunit in the cardiovascular system, we have analyzed beta3-null mice. Electrophysiological examinations proved the existence of dihydropyridine (DHP)-sensitive. L-type calcium channels in the smooth muscle cells. Beta3-null mice show no apparent changes in smooth muscle contraction and sensitivity to DHP, and normal blood pressure when they are raised on a normal diet, but the 13 subunit deficient mice show elevated blood pressure in response to a high-salt diet, with significant reductions in plasma catecholamine concentrations. Our finding strongly suggests a close relationship between voltage-dependent channels and high blood pressure.
Murakami
M
M
Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Japan. mmura@mail.cc.tohoku.ac.jp
Yamamura
H
H
Murakami
A
A
Okamura
T
T
Nunoki
K
K
Mitui-Saito
M
M
Muraki
K
K
Hano
T
T
Imaizumi
Y
Y
Flockerzi
T
T
Yanagisawa
T
T
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D015220:Calcium Channels / Q000502:physiology*; D006339:Heart Rate; D066298:In Vitro Techniques; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D021122:Protein Subunits; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*; D014661:Vasoconstriction / Q000187:drug effects*
D015220:Calcium Channels; D021122:Protein Subunits; D017673:Sodium Chloride, Dietary