Calcitonin gene-related peptide (CGRP) and leg vascular resistance during head-up tilt induced hypovolaemic shock in man.
Calcitonin gene-related peptide is a potent vasodilator and its distribution in perivascular nerves suggests a role in the regulation of vascular tone. We evaluated leg vascular resistance together with total peripheral resistance and the arterial plasma concentrations of calcitonin gene-related peptide and catecholamines during 50 degrees head-up tilt induced hypotension in 7 males. During tilt mean arterial pressure, heart rate, total peripheral resistance, leg vascular resistance and plasma noradrenaline increased, while cardiac output and leg blood flow decreased. After 45 +/- 9 min (mean +/- SE) presyncopal symptoms appeared together with decreases in mean arterial pressure (81 +/- 6 to 56 +/- 9 mmHg), heart rate (97 +/- 6 to 73 +/- 8 beats min-1), leg vascular resistance (158 +/- 9 to 109 +/- 8 mmHg min l-1) and total peripheral resistance (17 +/- 3 to 10 +/- 2 mmHg min l-1) (P less than 0.01). Plasma calcitonin gene-related peptide increased from 32 +/- 3 to 35 +/- 3 pmol l-1 (P less than 0.01) and adrenaline from 1.1 +/- 0.2 to 1.7 +/- 0.3 nmol l-1 (P less than 0.01), while noradrenaline did not change. The results indicate that presyncopal symptoms induced by head-up tilt are associated with regional as well as total decreases in vascular resistance accompanied by moderate increases in arterial plasma concentrations of calcitonin gene-related peptide and adrenaline.
Department of Medical Physiology C, Panum Institute, University of Copenhagen, Denmark.
S
S
Matzen
S
S
Schifter
J
J
Radvansky
U
U
Knigge
J
J
Warberg
N H
NH
Secher
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000097:blood* / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D002395:Catecholamines / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology; D007866:Leg / Q000098:blood supply*; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology; D012769:Shock / Q000097:blood / Q000503:physiopathology*; D013318:Stroke Volume / Q000502:physiology; D013575:Syncope / Q000503:physiopathology; D014655:Vascular Resistance / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology
D002395:Catecholamines; D015740:Calcitonin Gene-Related Peptide