AJP - Heart and Circulatory Physiology, Vol 272, Issue 5 2271-H2281, Copyright © 1997 by American Physiological Society

ARTICLES

Physiological variations in ovine cerebrovascular calcium sensitivity

S. E. Akopov, L. Zhang and W. J. Pearce
Department of Physiology, Loma Linda University School of Medicine, California 92350, USA.

Cerebrovascular reactivity to biogenic amines varies in relation to both arterial diameter and age. The present study examines the hypothesis that these patterns of reactivity are secondary to corresponding variations in the Ca2+ sensitivity of the contractile proteins. To test this hypothesis, we permeabilized segments of common carotid (Com), basilar, main branch middle cerebral, and second-branch middle cerebral (MCA-B) arteries from nonpregnant adult and near-term fetal sheep using beta-escin. Permeabilization methods were carefully validated and adjusted for each artery type. Baseline myofilament Ca2+ sensitivity in both adults and fetuses increased significantly from the Com to the MCA-B and was generally higher in fetuses than in adults. Serotonin dose dependently increased Ca2+ sensitivity via a G protein-dependent mechanism in all arteries. The magnitudes of this effect did not vary among artery types but were significantly greater in fetal than in adult arteries. This effect of serotonin was mimicked by guanosine 5'-O-(3-thiotriphosphate), a nonhydrolyzable analog of guanosine 5'-triphosphate, and its effects were also much greater in fetal than in adult arteries. We conclude that patterns of cerebrovascular reactivity to biogenic amines were determined, at least in part, by underlying variations in baseline myofilament Ca2+ sensitivity and/or its alteration by G protein-dependent mechanisms.

This article has been cited by other articles:

				R. J. Sandoval, E. R. Injeti, W. T. Gerthoffer, and W. J. Pearce Postnatal maturation modulates relationships among cytosolic Ca2+, myosin light chain phosphorylation, and contractile tone in ovine cerebral arteries Am J Physiol Heart Circ Physiol, October 1, 2007; 293(4): H2183 - H2192. [Abstract] [Full Text] [PDF]

				S. M. Charles, L. Zhang, L. D. Longo, J. N. Buchholz, and W. J. Pearce Postnatal maturation attenuates pressure-evoked myogenic tone and stretch-induced increases in Ca2+ in rat cerebral arteries Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2007; 293(2): R737 - R744. [Abstract] [Full Text] [PDF]

				R. J. Sandoval, E. R. Injeti, J. M. Williams, W. T. Georthoffer, and W. J. Pearce Myogenic contractility is more dependent on myofilament calcium sensitization in term fetal than adult ovine cerebral arteries Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H548 - H556. [Abstract] [Full Text] [PDF]

				M. T. Lin, D. A. Hessinger, W. J. Pearce, and L. D. Longo Modulation of BK channel calcium affinity by differential phosphorylation in developing ovine basilar artery myocytes Am J Physiol Heart Circ Physiol, August 1, 2006; 291(2): H732 - H740. [Abstract] [Full Text] [PDF]

				D. Xiao, X. Huang, L. D. Longo, W. J. Pearce, and L. Zhang Regulation of baseline Ca2+ sensitivity in permeabilized uterine arteries: effect of pregnancy Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H413 - H420. [Abstract] [Full Text] [PDF]

				S. M. Nauli, J. M. Williams, W. T. Gerthoffer, and W. J. Pearce Chronic hypoxia modulates relations among calcium, myosin light chain phosphorylation, and force differently in fetal and adult ovine basilar arteries J Appl Physiol, July 1, 2005; 99(1): 120 - 127. [Abstract] [Full Text] [PDF]

				M. T. Lin, L. D. Longo, W. J. Pearce, and D. A. Hessinger Ca2+-activated K+ channel-associated phosphatase and kinase activities during development Am J Physiol Heart Circ Physiol, July 1, 2005; 289(1): H414 - H425. [Abstract] [Full Text] [PDF]

				J. M. Williams, A. D. Hull, and W. J. Pearce Maturational modulation of endothelium-dependent vasodilatation in ovine cerebral arteries Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2005; 288(1): R149 - R157. [Abstract] [Full Text] [PDF]

				A. Ahmed, C. M. Waters, C. W. Leffler, and J. H. Jaggar Ionic mechanisms mediating the myogenic response in newborn porcine cerebral arteries Am J Physiol Heart Circ Physiol, November 1, 2004; 287(5): H2061 - H2069. [Abstract] [Full Text] [PDF]

				M. T. Lin, D. A. Hessinger, W. J. Pearce, and L. D. Longo Developmental differences in Ca2+-activated K+ channel activity in ovine basilar artery Am J Physiol Heart Circ Physiol, July 11, 2003; 285(2): H701 - H709. [Abstract] [Full Text] [PDF]

				S. M. Nauli, J. M. Williams, S. E. Akopov, L. Zhang, and W. J. Pearce Developmental changes in ryanodine- and IP3-sensitive Ca2+ pools in ovine basilar artery Am J Physiol Cell Physiol, December 1, 2001; 281(6): C1785 - C1796. [Abstract] [Full Text] [PDF]

				S. M. Nauli, L. Zhang, and W. J. Pearce Maturation depresses cGMP-mediated decreases in [Ca2+]i and Ca2+ sensitivity in ovine cranial arteries Am J Physiol Heart Circ Physiol, March 1, 2001; 280(3): H1019 - H1028. [Abstract] [Full Text] [PDF]

				D. M. Angeles, J. Williams, R. E. Purdy, L. Zhang, and W. J. Pearce Effects of maturation and acute hypoxia on receptor-IP3 coupling in ovine common carotid arteries Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2001; 280(2): R410 - R417. [Abstract] [Full Text] [PDF]

				D. M. Angeles, J. Williams, L. Zhang, and W. J. Pearce Acute hypoxia modulates 5-HT receptor density and agonist affinity in fetal and adult ovine carotid arteries Am J Physiol Heart Circ Physiol, August 1, 2000; 279(2): H502 - H510. [Abstract] [Full Text] [PDF]

				W. Long, Y. Zhao, L. Zhang, and L. D. Longo Role of Ca2+ channels in NE-induced increase in [Ca2+]i and tension in fetal and adult cerebral arteries Am J Physiol Regulatory Integrative Comp Physiol, July 1, 1999; 277(1): R286 - R294. [Abstract] [Full Text] [PDF]

				G. Q. Teng, J. Williams, L. Zhang, R. Purdy, and W. J. Pearce Effects of maturation, artery size, and chronic hypoxia on 5-HT receptor type in ovine cranial arteries Am J Physiol Regulatory Integrative Comp Physiol, September 1, 1998; 275(3): R742 - R753. [Abstract] [Full Text] [PDF]

				S. E. Akopov, L. Zhang, and W. J. Pearce Regulation of Ca2+ sensitization by PKC and rho proteins in ovine cerebral arteries: effects of artery size and age Am J Physiol Heart Circ Physiol, September 1, 1998; 275(3): H930 - H939. [Abstract] [Full Text] [PDF]

				L. Zhang and D. Xiao Effects of chronic hypoxia on Ca2+ mobilization and Ca2+ sensitivity of myofilaments in uterine arteries Am J Physiol Heart Circ Physiol, January 1, 1998; 274(1): H132 - H138. [Abstract] [Full Text] [PDF]