AJP - Heart and Circulatory Physiology, Vol 257, Issue 3 824-H833, Copyright © 1989 by American Physiological Society

ARTICLES

Direct effects of graded hypoxia on intact and denuded rabbit cranial arteries

W. J. Pearce, S. Ashwal and J. Cuevas
Department of Physiology, Loma Linda University School of Medicine, California 92350.

In isolated rabbit common carotid, internal carotid, and basilar arteries denuded of endothelium, mounted for measurement of contractile activity, and contracted with 10 microM serotonin (common and internal carotid) or 100 microM uridine 5'-triphosphate (UTP; basilar), 20 min of severe (PO2 = 15 Torr) and moderate (PO2 = 35 Torr) hypoxia relaxed initial tensions to 17, 6, and 16% and 18, 7, and 61% of control, respectively. The corresponding values in arteries contracted with 120 mM potassium-Krebs solution were 42, 60, and 73% and 57, 72, and 88%. These data indicate that the main determinants of the responses to hypoxia were intrinsic to the vessel walls of these arteries and that complete depolarization attenuated but did not eliminate the effects of these mechanisms. Superimposed on these intrinsic mechanisms were the effects of the endothelium, which were evaluated by several methods, including integration of the area between the 20-min response time courses of corresponding intact and denuded segments. Positive and negative integrated area values indicated endothelial vasoconstrictor [endothelium-derived contracting factor (EDCF)] and vasodilator [endothelium-derived relaxing factor (EDRF)] influences, respectively. In common carotid, internal carotid, and basilar segments contracted with serotonin and/or UTP, these areas averaged 770, 354, and 44 min% during severe and 491, 189, and -411 min% during moderate hypoxia. Corresponding values during potassium contraction were 217, -271, and -356 min% and 52, -177, and -54 min%. Together, these findings suggest that 1) intrinsic vascular mechanisms contribute significantly to hypoxic cerebral vasodilation in the rabbit, 2) EDCF is more prominent but also may be more sensitive to depolarization than EDRF, 3) hypoxia promotes the simultaneous release of both EDCF and EDRF, and 4) the ratio of EDCF to EDRF released during hypoxia decreases as one moves from the rabbit common carotid to the internal carotid to the basilar arteries.

This article has been cited by other articles:

				A. Kanu and C. W. Leffler Carbon monoxide and Ca2+-activated K+ channels in cerebral arteriolar responses to glutamate and hypoxia in newborn pigs Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H3193 - H3200. [Abstract] [Full Text] [PDF]

				W. Pearce Hypoxic regulation of the fetal cerebral circulation J Appl Physiol, February 1, 2006; 100(2): 731 - 738. [Abstract] [Full Text] [PDF]

				G. P. Nase, J. Tuttle, and H. G. Bohlen Reduced perivascular PO2 increases nitric oxide release from endothelial cells Am J Physiol Heart Circ Physiol, July 11, 2003; 285(2): H507 - H515. [Abstract] [Full Text] [PDF]

				Y. Liu, D. R. Harder, and J. H. Lombard Interaction of myogenic mechanisms and hypoxic dilation in rat middle cerebral arteries Am J Physiol Heart Circ Physiol, December 1, 2002; 283(6): H2276 - H2281. [Abstract] [Full Text] [PDF]

				W. J. Calvo, G. Hajduczok, J. A. Russell, and S. L. Diamond Inhibition of Nitric Oxide but Not Prostacyclin Prevents Poststenotic Dilatation in Rabbit Femoral Artery Circulation, March 2, 1999; 99(8): 1069 - 1076. [Abstract] [Full Text] [PDF]

				J. H. Lombard, M. P. Kunert, R. J. Roman, J. R. Falck, D. R. Harder, and W. F. Jackson Cytochrome P-450 omega -hydroxylase senses O2 in hamster muscle, but not cheek pouch epithelium, microcirculation Am J Physiol Heart Circ Physiol, February 1, 1999; 276(2): H503 - H508. [Abstract] [Full Text] [PDF]

				J. H. Lombard, Y. Liu, K. T. Fredricks, D. M. Bizub, R. J. Roman, and N. J. Rusch Electrical and mechanical responses of rat middle cerebral arteries to reduced PO2 and prostacyclin Am J Physiol Heart Circ Physiol, February 1, 1999; 276(2): H509 - H516. [Abstract] [Full Text] [PDF]

				G. Auer and M. E. Ward Impaired reactivity of rat aorta to phenylephrine and KCl after prolonged hypoxia: role of the endothelium J Appl Physiol, August 1, 1998; 85(2): 411 - 417. [Abstract] [Full Text] [PDF]

				J. A. Ulatowski, E. Bucci, A. Razynska, R. J. Traystman, and R. C. Koehler Cerebral blood flow during hypoxic hypoxia with plasma-based hemoglobin at reduced hematocrit Am J Physiol Heart Circ Physiol, June 1, 1998; 274(6): H1933 - H1942. [Abstract] [Full Text] [PDF]

				R. Gagnon, T. Lamb, and B. Richardson Cerebral circulatory responses of near-term ovine fetuses during sustained fetal placental embolization Am J Physiol Heart Circ Physiol, October 1, 1997; 273(4): H2001 - H2008. [Abstract] [Full Text] [PDF]