Vasodilatation of muscle microvessels induced by somatic afferent stimulation is mediated by calcitonin gene-related peptide release in the rat.
In anesthesized rats, the effects of electrical stimulation (ES) to the saphenous nerve on the microcirculation of the gracilis muscle were assessed through the measurement of two different hemodynamic parameters: (a). the muscle blood flow (MBF) using a laser Doppler flowmeter; and (b). the changes in diameter of the muscle arterioles observed directly using an intravital microscope system. Ipsilateral ES (5 V, 20 Hz, for 30 s) produced increases in MBF and mean arterial pressure (47+/-10% and 18+/-5%) over the baseline, while no significant changes in MBF were observed in the contralateral muscle. Neither selective nor simultaneous alpha- and beta-adrenergic blockade altered the increases in MBF induced by ipsilateral ES. The arteriolar diameter was found to increase by 38.9+/-5% following ipsilateral ES. This response in diameter was abolished after the topical application of a calcitonin gene-related peptide receptor antagonist (CGRP(8-37)). Contralateral ES produced a decrease in arteriolar diameter by 26+/-14%. Thus, ipsilateral nerve ES produced vasodilative responses in the muscle accompanied by increases in MBF independently of the sympathetic activity. Furthermore, CGRP was found directly involved in the reflex neural regulation of the muscle microcirculation, which suggests the participation of an axon reflex mechanism.
Loaiza
Lázaro A
LA
Department of Biomedical Engineering, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba Science City, Ibaraki 305-8575, Japan.
Yamaguchi
Shinjiro
S
Ito
Momoyo
M
Ohshima
Norio
N
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000037:antagonists & inhibitors*; D004558:Electric Stimulation; D007839:Functional Laterality; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects; D010446:Peptide Fragments / Q000037:antagonists & inhibitors*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011913:Rats, Inbred BB; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D010446:Peptide Fragments; C058636:calcitonin gene-related peptide (8-37); D011433:Propranolol; D015740:Calcitonin Gene-Related Peptide; D010646:Phentolamine