Hypertension is a major health problem which accounts for a significant degree of morbidity and mortality in our population. Both structural and functional changes in the vasculature are believed to contribute to the genesis and maintenance of this disease. Reports of disturbances in Ca2+ homeostasis in several organ systems of both the essential hypertensive human and the spontaneously hypertensive rat (SHR) have served as the basis for the hypothesis that variations in the levels of serum 1,25 VitD, parathyroid hormone (PTH) or calcitonin alter functional properties of vascular muscle. Until recently, however, the vascular effects of these hormones had not been investigated. Our laboratory has found that 1,25 VitD increases 45Ca uptake in cultured aortic myocytes of the SHR and the Wistar Kyoto (WKY) control. 1,25 VitD and PTH were found to differentially modulate norepinephrine (NE)- induced changes in intracellular-free (Ca2+)i in resistance arteries of the SHR and WKY. 1,25 VitD has also been found to modulate growth of vascular myocytes in culture. Our findings have prompted the hypothesis that the calciotropic hormones 1,25 VitD and PTH as well as calcitonin and calcitonin gene-related peptide (CGRP) are modulators of vascular cell contractility, Ca2+ metabolism and growth. A derivative hypothesis is that vascular muscle of the SHR is differentially sensitive to these agents. These hypotheses will be experimentally tested. The effects of 1,25 VitD, PTH, calcitonin and CGRP on contractility and (Ca2+)i of mesenteric resistance arteries will be assessed using a wire myograph and the intracellular dye Fura-2. The effects of these hormones on cellular Ca2+ metabolism will be assessed using both primary and passaged cultures of mesenteric artery myocytes. Indices of Ca2+ metabolism that will be assessed include 45Ca uptake and agonist-induced changes in free (Ca2+)i. Calciotrophic hormone effects on cell growth will be assessed by measuring their effect on both basal and growth factor-induced proliferation. Cellular mechanisms to be examined which might underlie the growth- related actions of these hormones include generation of the inositol polyphosphates and induction of transient changes in free (Ca2+)i and pH. In summary, these experiments will examine metabolism and growth; the results may provide a basis for the development of new perspectives on blood pressure control.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HL041816-05
Application #
2220166
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1991-12-12
Project End
1994-11-30
Budget Start
1992-12-01
Budget End
1994-11-30
Support Year
5
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Li, J; Bian, K A; Bukoski, R D (1994) A non-cyclo-oxygenase, non-nitric oxide relaxing factor is present in resistance arteries of normotensive but not spontaneously hypertensive rats. Am J Med Sci 307:7-14
Bukoski, R D; Lastelic, B A; Xue, H et al. (1994) Intracellular Ca2+ and force generation determined in resistance arteries of normotensive and hypertensive rats. J Hypertens 12:15-21
Bukoski, R D; Xue, H (1993) On the vascular inotropic action of 1,25-(OH)2 vitamin D3. Am J Hypertens 6:388-96
Li, J; Bukoski, R D (1993) Endothelium-dependent relaxation of hypertensive resistance arteries is not impaired under all conditions. Circ Res 72:290-6
Bukoski, R D; Bo, J; Xue, H et al. (1993) Antiproliferative and endothelium-dependent vasodilator properties of 1,3-dihydro-3-p-chlorophenyl-7-hydroxy-6-methyl-furo-(3,4c) pyridine hydrochloride (cicletanine). J Pharmacol Exp Ther 265:30-5
Bukoski, R D; Li, J; Bo, J (1993) Effect of long-term administration of 1,25 (OH)2 vitamin D3 on blood pressure and resistance artery contractility in the spontaneously hypertensive rat. Am J Hypertens 6:944-50
Schleiffer, R; Xue, H; McCarron, D A et al. (1993) Effect of chronic and subacute parathyroidectomy on blood pressure and resistance artery contractility in the spontaneously hypertensive rat. J Hypertens 11:709-16
Andriantsitohaina, R; Bian, K; Stoclet, J C et al. (1993) Neuropeptide Y increases force development through a mechanism that involves calcium entry in resistance arteries. J Vasc Res 30:309-14
Li, J; Ehrenfried, L K; Bukoski, R D (1993) Changes in extracellular Ca2+ over a physiologic concentration range differentially modulate reactivity of resistance arteries of spontaneously hypertensive and normotensive rats. Clin Exp Hypertens 15:849-66
Oshima, T; Young, E W; Bukoski, R D et al. (1991) Rise and fall of agonist-evoked platelet Ca2+ in hypertensive rats. Hypertension 18:758-62

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