L-arginine or papaverine infusion caused transient vasodilation and disappearance of vasomotion waves, increasing capillary blood flow by 273% and 239% of baseline values for short and long terminal arteriolar trees, respectively.
Does L-arginine or papaverine alter arteriolar rhythmic diameter changes and capillary perfusion in hamster skeletal muscle microcirculation?
Capillary blood flow in hamster skeletal muscle is modulated by rhythmic diameter changes of terminal arterioles, which can be abolished by vasodilators like L-arginine or papaverine to induce continuous perfusion.
rhythmic diameter changes of arterioles to clarify regulatory mechanisms of the capillary perfusion. The experimental study was carried out in male Syrian hamsters implanted with a plastic chamber in the dorsum skin under pentobarbital anesthesia. The skeletal muscle microvessels were visualized by fluorescence microscopy. The vessel diameters, lengths and the rhythmic diameter changes of arterioles were analyzed with computer-assisted techniques. The arterioles were classified according to a centripetal ordering scheme. In hamster skeletal muscle microvasculature the terminal branchings, differentiated in long and short terminal arteriolar trees (TATs), originated from anastomotic vessels, defined "arcading" arterioles. The long TATs presented different frequencies along the branching vessels; order 4 arterioles had frequencies lower than those observed in the order 3, 2, and 1 vessels. The short TAT order 3 arterioles, directly originating from "arcading" parent vessels, showed a frequency dominating all daughter arterioles. The amplitude of diameter variations in larger vessels was in the range 30-40% of mean diameter, while it was 80-100% in order 3, 2, and 1 vessels. Therefore, the complete constriction of arterioles, caused an intermittent capillary blood perfusion. L-arginine or papaverine infusion caused dilation of arterioles and transient disappearing of vasomotion waves and induced perfusion of all capillaries spreading from short and long TAT arrangements. Therefore, the capillary blood flow was modulated by changes in diameter of terminal arterioles penetrating within the skeletal muscle fibers, facilitating redistribution of blood flow according to the metabolic demands of tissues.
Lapi et al. (Fri,) conducted a other in Healthy (skeletal muscle microcirculation) (n=11). L-arginine or papaverine vs. Baseline conditions was evaluated on Capillary blood flow and arteriolar rhythmic diameter changes. L-arginine or papaverine infusion caused transient vasodilation and disappearance of vasomotion waves, increasing capillary blood flow by 273% and 239% of baseline values for short and long terminal arteriolar trees, respectively.