| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Vascular Cell Biology Laboratory, Dalton Cardiovascular Research Center, and Departments of Physiology and Veterinary Biomedical Sciences, University of Missouri, Columbia, Missouri 65211
Heterogeneity of vascular responses to
physiological and pharmacological stimuli has been demonstrated
throughout the coronary circulation. Typically, this heterogeneity is
based on vessel size. Although the cellular mechanisms for this
heterogeneity are unknown, one plausible factor may be heterogeneous
distribution of ion channels important in regulation of vascular tone.
Because of the importance of voltage-gated
Ca2+ channels in regulation of
vascular tone, we hypothesized that these channels would be unequally
distributed throughout the coronary arterial bed. To test this
hypothesis, voltage-gated Ca2+
current was measured in smooth muscle from conduit arteries (>1.0 mm), small arteries (200-250 µm), and large arterioles
(75-125 µm) of miniature swine using whole cell voltage-clamp
techniques. With 2 mM Ca2+ or 10 mM Ba2+ as charge carrier,
voltage-gated Ca2+ current density
was inversely related to arterial diameter, i.e., large arterioles > small arteries > conduit. Peak inward currents (10 mM
Ba2+) were increased ~2.5- and
~1.5-fold in large arterioles and small arteries, respectively,
compared with conduit arteries (
5.58 ± 0.53, 3.54 ± 0.34, and 2.26 ± 0.31 pA/pF, respectively). In physiological Ca2+ (2 mM), small
arteries demonstrated increased inward current at membrane potentials
within the physiological range for vascular smooth muscle (as negative
as 40 mV) compared with conduit arteries. In addition, cells
from large arterioles showed a negative shift in the membrane potential
for half-maximal activation compared with small and conduit arteries
(13.23 ± 0.88, 6.22 ± 1.35, and 8.62 ± 0.81 mV, respectively; P < 0.05).
Voltage characteristics and dihydropyridine sensitivity identified this
Ca2+ current as predominantly
L-type current in all arterial sizes. We conclude that L-type
Ca2+ current density is inversely
related to arterial diameter within the coronary arterial vasculature.
This heterogeneity of Ca2+ current
density may provide, in part, the basis for functional heterogeneity
within the coronary circulation.
voltage clamp; dihydropyridine; vascular smooth muscle
This article has been cited by other articles:
|
|
 |
|
  C. A. Witczak, B. R. Wamhoff, and M. Sturek Exercise training prevents Ca2+ dysregulation in coronary smooth muscle from diabetic dyslipidemic yucatan swine J Appl Physiol, September 1, 2006; 101(3): 752 - 762. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. A. Mokelke, N. J. Dietz, D. M. Eckman, M. T. Nelson, and M. Sturek Diabetic dyslipidemia and exercise affect coronary tone and differential regulation of conduit and microvessel K+ current Am J Physiol Heart Circ Physiol, March 1, 2005; 288(3): H1233 - H1241. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Bowles, K. K. Maddali, V. K. Ganjam, L. J. Rubin, D. L. Tharp, J. R. Turk, and C. L. Heaps Endogenous testosterone increases L-type Ca2+ channel expression in porcine coronary smooth muscle Am J Physiol Heart Circ Physiol, November 1, 2004; 287(5): H2091 - H2098. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Heaps, J. L. Parker, M. Sturek, and D. K. Bowles Altered calcium sensitivity contributes to enhanced contractility of collateral-dependent coronary arteries J Appl Physiol, July 1, 2004; 97(1): 310 - 316. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Bowles, C. L. Heaps, J. R. Turk, K. K. Maddali, and E. M. Price Hypercholesterolemia inhibits L-type calcium current in coronary macro-, not microcirculation J Appl Physiol, June 1, 2004; 96(6): 2240 - 2248. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Heaps and D. K. Bowles Nonuniform changes in arteriolar myogenic tone within skeletal muscle following hindlimb unweighting J Appl Physiol, March 1, 2002; 92(3): 1145 - 1151. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Heaps and D. K. Bowles Gender-specific K+-channel contribution to adenosine-induced relaxation in coronary arterioles J Appl Physiol, February 1, 2002; 92(2): 550 - 558. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Bowles Gender influences coronary L-type Ca2+ current and adaptation to exercise training in miniature swine J Appl Physiol, December 1, 2001; 91(6): 2503 - 2510. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Bowles, Q. Hu, M. H. Laughlin, and M. Sturek Exercise training increases L-type calcium current density in coronary smooth muscle Am J Physiol Heart Circ Physiol, December 1, 1998; 275(6): H2159 - H2169. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
