Calcium dynamics and vasomotion in rat mesenteric arteries.
Smooth muscle cell calcium dynamics and diameter were measured in intact pressurized rat mesenteric artery segments during vasoconstriction and vasomotion. Arteries showed a certain norepinephrine (NE) threshold (0.3-0.4 microM) for the onset of vasomotion, during a cumulative NE concentration-response curve. This was due to a necessary [Ca2+]i threshold (increase over basal level of 22.2 +/- 2.6%) to elicit oscillations. The calcium oscillations obtained were synchronous over the entire vessel length and phase-shifted (in advance by 1.7 +/- 0.3 seconds) with respect to the diameter oscillations. A similar result was obtained using a KCl depolarization to contract the arteries, even though the [Ca2+]i threshold was much smaller in this case (increase over basal level of 9.9 +/- 4.3%), as compared with the NE-elicited vasomotion. Blockade of the Na+/K+-ATPase with 1 microM ouabain, or of the Na+/Ca2+ exchanger (NCX) with 1 microM KB-R 7943, did not abolish the calcium oscillations, thus showing that these two pumps are only modulatory elements, while on the other hand, voltage-gated calcium channels have been found to be important in the vasomotion mechanism.
Schuster
Alexander
A
Cellular Biophysics and Biomechanics Laboratory, Swiss Federal Institute of Technology, Lausanne, Switzerland. schuster@bioeng.ucsd.edu
Lamboley
Mathieu
M
Grange
Céline
C
Oishi
Hirotaka
H
Bény
Jean-Louis
JL
Stergiopulos
Nikolaos
N
Meister
Jean-Jacques
JJ
D000818:Animals; D002118:Calcium / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000502:physiology; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D014666:Vasomotor System / Q000187:drug effects* / Q000502:physiology
C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D019831:Sodium-Calcium Exchanger; D013890:Thiourea; D002118:Calcium