Fig. 3. Respiration of crocodile salt gland slices from freshwater- (black bars) or saltwater- (grey bars) acclimated C. porosus and the effect of 0.1 mmol l^–1 methacholine chloride on salt gland tissue oxygen consumption rate. Values are means ± s.e.m.; N=5 per treatment. Asterisks indicate a significant difference between control and methacholine treatments at the level of P<0.05.