NHE-1 activity was assessed by evaluating the rate of pHi
recovery from an ammonium pre-pulse-induced acid load [20]. Transient
(3 min) exposure of myocytes to 20 mM NH4Cl was used for this
purpose. Proton efflux (JH) was calculated as dpHi/dt x βi and comparison
among different groupswas done at a common pHi of 6.8