Figure 4. Effects of acidification of the diaphragm via lactic acid injection into the phrenic artery during mild intensity exercise in the chronically instrumented canine (n = 7).

Note that the injection of lactic acid elicited an average increase in MAP of 20% and a decrease in limb vascular conductance of 30% and blood flow of 20%. These vasoconstrictor effects of diaphragm acidification were prevented via sympathetic blockade. Data obtained from Rodman et al. (2003). MAP, mean arterial blood pressure; CO, cardiac output.