Key Points
- The aim is to investigate the proton net efflux mechanisms through the Na+-H+ exchanger in rat heart myocytes.
- Isolated ventricular myocytes from adult rat heart were prepared and subjected to pH measurements using BCECF dye.
- Proton efflux was characterized via the ammonium chloride prepulse technique under varying conditions of pHo and pHi.
- Effects of ammonium chloride and amiloride on proton movements were evaluated to assess competitive inhibition.
- Steady-state pHi was determined to be 7.16 ± 0.11 at 37°C in bicarbonate-free media.
- Proton extrusion was significantly stimulated by extracellular sodium with K1/2 = 58 ± 16 mM and maximal recovery rate of 55 ± 7 mmol/(1 cell H2O.min).
- Amiloride inhibited >90% of proton movements with an inhibition constant of 3.5 µM.
Structured PICO
PPopulationVentricular myocytes isolated from adult rat heart
IInterventionAmmonium chloride prepulse technique to acidify intracellular pH, followed by measurement of proton net efflux
OOutcomeKinetics of proton net efflux via the Na+-H+ exchanger (rate of return to resting intracellular pH)surrogate
This preclinical study characterizes the kinetics of the Na+-H+ exchanger in adult rat ventricular myocytes, highlighting its regulation by intracellular and extracellular protons and sodium.