Jl. Bailey et al., INFLUENCE OF ACID LOADING, EXTRACELLULAR PH AND UREMIA ON INTRACELLULAR PH IN MUSCLE, Mineral and electrolyte metabolism, 22(1-3), 1996, pp. 66-68
Our previous work has shown that chronic metabolic acidosis can induce
changes in protein and amino acid metabolism in muscle. The relations
hip of these metabolic responses to changes in muscle pH is unknown. T
o examine the role that acute acidosis might have on intracellular pH
in rats, we evaluated the influence an acute infusion of HCl has on in
tracellular pH using P-31-NMR. Male rats fed 22% protein and weighing
between 150 and 170 g were infused with 150 mM HCl 94 mmol/kg) over a
2- or 4-hour period. Baseline blood pH was 7.36 and dropped to 7.04 at
the end of the infusion. Despite this, no changes in intracellular pH
were seen. In contrast, we found that chronic acid loading (4 mmol (N
HCl)-Cl-4/100 g/day for 5 days) produces a small change in muscle pH (
0.05 pH units, p<0.05). Chronic uremia did not change resting muscle p
H despite a decrease in extracellular pH to 7.23 even though metabolic
changes are well documented. Conclusions: (1) An acute acid load does
not alter intracellular pH while chronic metabolic acidosis does redu
ce intracellular pH. (2) The lack of acute change in intracellular pH
suggests that intracellular buffering capacity changes over time.