Acetylcholine is a vasodilator of porcine skeletal muscle arteries.
The purpose of this study was to test the hypothesis that porcine skeletal muscle arteries exhibit concentration-dependent vasodilation in response to acetylcholine (ACH) as observed in other mammals. We conducted three experiments. First, vasorelaxation responses to ACH were examined in isolated segments of femoral and brachial arteries, mounted on myographs and studied in vitro. Second, we determined whether resistance arteries from porcine skeletal muscle exhibit vasodilation in response to ACH by isolating second order arterioles (2-A) from the medial (MHT), deep-long (LOH) and lateral (LAT) heads of the triceps brachii muscles of four pigs. The rationale for selection of arterioles from these muscles was that these muscles represent muscles composed primarily of slow-oxidative, fast-oxidative-glycolytic, and fast-glycolytic muscle fiber types, respectively. 2-As were isolated and cannulated with micropipettes and intraluminal pressure set at 60 cm H2O. In both sets of in vitro experiments, we determined responses to an endothelium-independent dilator, sodium nitroprusside (10(-10)-10(-4) M), and to endothelium-dependent agents ACH (10(-10)-10(-4) M), and bradykinin (BK; 10(-11)-10(-6) M). Third, we used transcutaneous ultrasound imaging to measure changes in artery diameters and Doppler-principle measurements of blood flow velocities to estimate changes in total blood flow in the femoral vascular bed. Results reveal that ACH and BK produced similar vasorelaxation responses in femoral and brachial arteries and vasodilation of skeletal muscle 2-As. Also, ACH produced increases in blood flow and decreases in vascular resistance in the femoral vascular bed. These results indicate that the arterial tree of porcine skeletal muscle exhibits ACH-induced, endothelium-dependent vasodilation.
Department of Veterinary Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia 65211, USA.
M H
MH
Laughlin
R M
RM
McAllister
J L
JL
Jasperse
L S
LS
Hitchcock
J D
JD
Bonagura
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D018482:Muscle, Skeletal / Q000098:blood supply*; D012039:Regional Blood Flow / Q000187:drug effects; D013552:Swine; D013556:Swine, Miniature; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; D000109:Acetylcholine