KCa-channel blockade prevents sustained pressure-induced depolarization in rat mesenteric small arteries

The American Journal of Physiology
J P WesselmanM J Mulvany

Abstract

In small blood vessels, elevation of transmural pressure induces myogenic constrictions and smooth muscle depolarization. The role of calcium-activated K+ channels (KCa channels) in these responses was examined in cannulated rat mesenteric small arteries. Inner and outer diameter were continuously monitored with a video technique. Smooth muscle membrane potential was recorded simultaneously using microelectrodes. To test for myogenic responsiveness, the transmural pressure was changed stepwise in the range between 10 and 120 mmHg. Pressure elevation induced moderate myogenic responses and significant depolarization, from -54.5 +/- 0.4 (SE) mV (n = 56) at 10 mmHg to -47.3 +/- 1.8 mV (n = 12) at 120 mmHg. Norepinephrine (NE, 0.67 and 10 microM) induced constriction and vasomotion, augmented myogenic responsiveness, and shifted the pressure-membrane potential relation to more depolarized values. Blockade of the Kca channels with charybdotoxin (ChTX) suppressed the responsiveness to pressure. In the absence of ChTX, with 0.67 microM NE, pressure elevation from 10 to 120 mmHg induced depolarization from -46.9 +/- 1.0 (n = 16) to -35.8 +/- 0.7 (n = 12) mV, whereas because of the myogenic response, the diameter increased only by 7%. I...Continue Reading

Citations

Mar 15, 2001·American Journal of Physiology. Heart and Circulatory Physiology·X Wu, M J Davis
Oct 23, 2001·American Journal of Physiology. Heart and Circulatory Physiology·S ChlopickiM J Mulvany
May 3, 2005·American Journal of Physiology. Heart and Circulatory Physiology·Neela Kotecha, Michael A Hill
Sep 16, 2006·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Linda MagnussonMax Salomonsson
Dec 3, 2010·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Saad EnouriRon Johnson
May 18, 2001·American Journal of Physiology. Heart and Circulatory Physiology·K A Dora, C J Garland
Jul 19, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Kim A DoraChristopher J Garland
Apr 18, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Ian N BratzNancy L Kanagy
Jun 24, 2004·Circulation·Virginia A ImadojemuLawrence I Sinoway
Oct 22, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Scott Earley, Benjimen R Walker
Oct 22, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Ed VanBavelBoye L Jensen
Jan 9, 2007·American Journal of Physiology. Heart and Circulatory Physiology·Rob H P Hilgers, R Clinton Webb
Dec 25, 2004·Circulation Research·Frances PlaneWilliam Cole
Mar 21, 2007·American Journal of Physiology. Heart and Circulatory Physiology·Jens Christian Brings JacobsenNiels-Henrik Holstein-Rathlou
Oct 22, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Jin ZhangMordecai P Blaustein
Apr 3, 2015·Physiological Reviews·Mattias CarlströmWilliam J Arendshorst

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