title: Vascular reactivity to calcitonin gene-related peptide is enhanced in subtotal nephrectomy-salt induced hypertension.
abstract: In subtotal nephrectomy (SN)- and salt-induced hypertension, calcitonin gene-related peptide (CGRP) plays a compensatory role to attenuate the blood pressure increase in the absence of an increase in the neuronal synthesis and release of this peptide. Therefore, the purpose of this study was to determine whether the mechanism of this antihypertensive activity is through enhanced sensitivity of the vasculature to the dilator actions of this neuropeptide. Hypertension was induced in Sprague-Dawley rats by SN and 1% saline drinking water. Control rats were sham-operated and given tap water to drink. After 11 days, rats had intravenous (drug administration) and arterial (continuous mean arterial pressure recording) catheters surgically placed and were studied in a conscious unrestrained state. Baseline mean arterial pressure was higher in the SN-salt rats (157 ± 5 mmHg) compared with controls (128 ± 3 mmHg). Administration of CGRP (and adrenomedullin) produced a significantly greater dose-dependent decrease in mean arterial pressure in SN-salt rats compared with controls (∼2.0-fold for both the low and high doses). Interestingly, isolated superior mesenteric arterioles from SN-salt rats were significantly more responsive to the dilator effects of CGRP (but not adenomedullin) than the controls (pEC(50), SN-salt, 14.0 ± 0.1 vs. control, 12.0 ± 0.1). Analysis of the CGRP receptor proteins showed that only the receptor component protein was increased significantly in arterioles from SN-salt rats. These data indicate that the compensatory antihypertensive effects of CGRP result from an increased sensitivity of the vasculature to dilator activity of this peptide. The mechanism may be via the upregulation of receptor component protein, thereby providing a more efficient coupling of the receptor to the signal transduction pathways.
authors.affiliation: Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina, USA. Scott.Supowit@uscmed.sc.edu
authors.forename: Scott C
authors.initials: SC
authors.lastname: Supowit
authors.forename: Khurshed A
authors.initials: KA
authors.lastname: Katki
authors.forename: Travis W
authors.initials: TW
authors.lastname: Hein
authors.forename: Prakash
authors.initials: P
authors.lastname: Gupta
authors.forename: Lih
authors.initials: L
authors.lastname: Kuo
authors.forename: Ian M
authors.initials: IM
authors.lastname: Dickerson
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Dipette
mesh_terms: D053607:Adrenomedullin / Q000008:administration & dosage; D000704:Analysis of Variance; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D001160:Arterioles / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects; D015153:Blotting, Western; D015740:Calcitonin Gene-Related Peptide / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D007262:Infusions, Intravenous; D008297:Male; D008643:Mesentery / Q000098:blood supply*; D009392:Nephrectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000819:agonists / Q000378:metabolism; D017673:Sodium Chloride, Dietary; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D000959:Antihypertensive Agents; D018015:Receptors, Calcitonin Gene-Related Peptide; D017673:Sodium Chloride, Dietary; D014665:Vasodilator Agents; D053607:Adrenomedullin; D015740:Calcitonin Gene-Related Peptide