Intracellular pH, H ion flux and H ion permeability coefficient in bullfrog toe muscle

EFFECTS OF pH ON THE PROCESSES OF EXCITATION-CONTRACTION COUPLING OF BULLFROG ATRIUM

“…The hydrogen ion, having the smallest diameter of all ions, is thus supposed to have extremely high membrane permeability. The experimental fact that, in skeletal muscle, H+ ion flux is about 1,000 times larger than that of K+ ions (IZUTSU, 1972) supports this view. If this is the case, the membrane permeabilities of cations other than the H+ ion should be under the control of the H+ ions.…”

Effects of extracellular pH, PCO2 and HCO3‐ on intracellular pH in isolated type‐I cells of the neonatal rat carotid body.

“…is again steep and almost identical to that found in respiratory acidosis/alkalosis (Fig. 2) Thomas, 1976;VaughanJones, 1986; slope 02-0-3), mammalian skeletal muscle (Aickin & Thomas, 1977; slope -0 3), rat dorsal root ganglion cells (Tolkovsky & Richards, 1987;slope 0-2) and guinea-pig vas deferens (estimated from Aickin, 1984;slope 0-35 A steep pH1/pH0 relationship was claimed originally for frog skeletal muscle (Izutsu, 1972) but this could not be confirmed by Bolton & Vaughan-Jones (1977) who found that the change of pHi was, at most, only about 40 % of the extracellular change. A recent report by Putnam & Grubbs (1990) (Meech & Thomas, 1987) and Ambystoma oocytes (Baud & Barish, 1984) this influx can be considerable, especially following depolarization of the membrane.…”

Intracellular pH and distribution of weak acids across cell membranes. A study of D‐ and L‐lactate and of DMO in rat diaphragm.

“…Exposure for 2-3 hr to ouabain in doses sufficient to raise fibre Na by 50 mm after 3 hr had no effect on pHi, either under normal conditions or with acid loads (Table 5). The absence of effect under normal conditions is not surprising: even if proton extrusion had been brought to a halt, a proton influx sufficient to produce demonstrable reduction in pHi requires many hours (Conway, 1957;Caldwell, 1958;Roos, 1971), although membrane permeability to H ions may be much greater than that to K (Woodbury, White, Mackey & Weakly, 1968;Izutsu, 1972). However, the absence of effect with acid loading indicates insensitivity of the proton pumping mechanism to the drug.…”