Role of membrane potential in vasomotion of isolated pressurized rat arteries.
Vasomotion, the phenomenon of vessel diameter oscillation, regulates blood flow and resistance. The main parameters implicated in vasomotion are particularly the membrane potential and the cytosolic free calcium in smooth muscle cells. In this study, these parameters were measured in rat perfused-pressurized mesenteric artery segments. The application of norepinephrine (NE) caused rhythmic diameter contractions and membrane potential oscillations (amplitude; 5.3 +/- 0.3 mV, frequency; 0.09 +/- 0.01 Hz). Verapamil (1 microM) abolished this vasomotion. During vasomotion, 10(-5) M ouabain (Na(+)-K(+) ATPase inhibitor) decreased the amplitude of the electrical oscillations but not their frequency (amplitude; 3.7 +/- 0.3 mV, frequency; 0.08 +/- 0.002 Hz). Although a high concentration of ouabain (10(-3) M) (which exhibits non-specific effects) abolished both electrical membrane potential oscillations and vasomotion, we conclude that the Na+-K+ ATPase could not be implicated in the generation of the membrane potential oscillations. We conclude that in rat perfused-pressurized mesenteric artery, the slow wave membrane type of potential oscillation by rhythmically gating voltage-dependent calcium channels, is responsible for the oscillation of intracellular calcium and thus vasomotion.
Oishi
Hirotaka
H
Department of Zoology and Animal Biology, University of Geneva, Switzerland.
Schuster
Alexander
A
Lamboley
Mathieu
M
Stergiopulos
Nikos
N
Meister
Jean-Jacques
JJ
Bény
Jean-Louis
JL
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology*; D014700:Verapamil / Q000494:pharmacology
D010042:Ouabain; D014700:Verapamil; D002118:Calcium; D009638:Norepinephrine