ARTERIOLE CONSTRICTION FOLLOWING ISCHEMIA IN DENERVATED SKELETAL-MUSCLE

Arteriolar diameters and flow patterns were determined in the isolated rat cremaster muscle following 4 hr of total ischemia. Two groups of six rats each were studied-an innervated group and a denervated group. The microcirculation was observed using intravital microscopy, and the images were recorded on videotape. The whole arterial tree was scanned, and the smallest vessel diameter for each arterial segment was measured. Preischemic mean arteriole diameters were significantly larger in the denervated group, compared to the innervated group. Following ischemia, during the 3 hr of reperfusion, the main (A1) cremaster arteriole from both the innervated and denervated groups constricted to 50 to 70 percent of pre-ischemic diameters. However, the actual diameters (as distinct from percentage change) were not significantly different between the innervated and denervated groups. There were significant differences in now patterns. Some A2 and A3 vessels became temporarily nonflowing vessels (either open but without flow, or closed by severe spasm). These poorly-functioning vessels were significantly more common in the denervated group. Furthermore, this phenomenon of temporary no-now persisted longer in the denervated group over the 3-hr reperfusion period. These observations suggest that the ability to recover quickly from an ischemic insult is less in tissues that have been denervated.