Is the Second Sodium Pump Electrogenic?

Table 1

ATPase activities of microsomal fraction from MDCK cells.

Conditions	Mg^2+	Mg^2+ + Na^+	Mg^2+ + Na^+ + K^+
Control	49.25 ± 1.65	93.29 ± 2.42	183.88 ± 10.31
Ouabain	49.52 ± 2.64	90.73 ± 3.33	95.76 ± 4.20
Ouabain + furosemide	52.94 ± 3.06	53.26 ± 3.30	55.54 ± 4.12

Results are expressed in nmoles Pi Lib./min*mg of protein and represent mean ± SEM of seven independent preparations.