Interspecific comparison of subcutaneous tissue fluid pressure in the bat wing

Tissue fluid pressures were recorded from subcutaneous tissues of three bat species by means of an improved servo-micropipet pressure recording system. Experimental animals were restrained but unanesthetized during the procedure by methods which avoided vascular occlusion. Tissue fluid pressures averaged +0.46 +/- 2.08 mm Hg (n = 12) in the Mexican free-tailed bat, +0.21 +/- 0.63 mm Hg (n = 14) in the pallid bat, and -0.31 +/- 1.01 mm Hg (n = 12) in the little brown bat. None of the average values differed significantly (P greater than 0.25) from the others or from atmospheric pressure (P greater than 0.20). Tissue fluid pressures in the subcutis of the bat were near atmospheric in agreement with the results obtained in the bat and other species by earlier investigators using both hypodermic needles and micropipets.