Comparison of neural controls of resistance and capillary density in resting muscle.

HONIG, CARL R., JAMES L. FRIERSON, AND JOHN L. PATTERSON. Comparison of neural controls of resistance and capillary density in resting muscle. Am. J. Physiol. 218(4) : 937-942. 1970.-The number of open capillaries was measured by direct enumeration in resting rat gracilis muscle in situ and found to be unchanged by acute denervation. When correlated with changes in resistance, results indicate that vasoconstrictor nerves influence arterioles, but not precapillary sphincters, in resting skeletal muscle. Counter-current blood flow was identified in some closely spaced capillaries both before and after denervation. Discussion considers the interplay between neural and local controls of arterioles and precapillary sphincters, and the possible impact of arrangement and number of open capillaries on the diffusional component of transport.