REGIONAL BLOOD FLOWS IN THE GOAT LATISSIMUS-DORSI MUSCLE BEFORE AND AFTER CHRONIC STIMULATION

Latissimus dorsi muscle (LDM) regional blood flows were determined in anesthetized goats by using colored microspheres under noncontracting and contracting conditions, either before or after 8-10 wk of chronic muscle stimulation. Surgical dissection of the LDM, leaving only the t horacodorsal artery to supply the muscle, did not alter regional nonco ntracting blood flows but significantly reduced the normal hyperemic r esponse to muscle contraction in muscle regions (posterior-medial) fur thest from the entrance of the thoracodorsal artery. Eight to 10 wk af ter acute muscle dissection, posterior-medial hyperemic flows were res tored. Chronic stimulation of the LDM for 8-10 wk, in either dissected or nondissected muscles, did not alter regional blood flows in noncon tracting muscle; however, it significantly reduced hyperemic flows in all muscle regions, although capillary density was increased and the m uscle was transformed into a predominantly type I fiber type. These re sults, coupled with data from previous experiments, suggest that the m uscle damage observed in the posterior-medial regions of the LDM after surgical dissection and chronic stimulation may be related to reduced hyperemic flow responses caused by surgical isolation of the muscle.