Blood flow in the rabbit tenuissimus muscle. Influence of preparative procedures for intravital microscopic observation.

The tenuissimus muscle in the rabbit and the cat is a suitable tissue for intravital microscopic investigation of skeletal muscle blood flow. In this study the influence of surgical procedures necessary for direct microscopic observation on the physiological state of the rabbit tenuissimus muscle was assessed by means of blood flow measurements. Mean resting blood flow was 2.8 +/0 0.8 (mean +2- S.D.) ml.min-1.100 g-1 in the left tenuissimus muscle when prepared for microscopic observation as determined by the radioactive microsphere method. This value was not significantly different from that in the intact unexposed muscle in the contralateral leg, 3.3 +/- 1.1. ml.min-1.100 g-1. Exposure of the muscle to atmospheric oxygen tension resulted in a reduction of blood flow to 0.7 +/- 0.4 ml.min-1.100 g -1, suggesting that local metabolic control mechanisms were active. The normal range of vascular control seemed to be maintained, as demonstrated by an increase in blood flow to 64.2 +/- 18.8 ml.min-1.100 g-1 during "maximal" vasodilation induced by topical application of PGE1. The tenuissimus muscle showed a marked sensitivity to mechanical stimulation. Slight stretching of the muscle, similar to what may occur during surgical preparation, resulted in an increase in blood flow to 17.5 +/- 5.7 ml.min-1.100 g-1. Flow values calculated from data obtained by direct microscopic measurements in the tenuissimus muscle agreed well with those obtained by the microsphere method.