Effects of 2,4-dinitrophenol (DNP) on the relationship between the chemosensory activities of the rat carotid body and the intracellular calcium of glomus cells.

To test the hypothesis that the uncoupler 2,4-dinitrophenol (DNP) increases [Ca2+]i equally well, independent of pHi, we studied the effects of 250 microM DNP on [Ca2+]i and carotid sinus nerve (CSN) activity of rat carotid body (CB). CSN activity was measured in CB perfused and superfused with hypocapnic (pHo 7.80) and normocapnic (pHo 7.42) Tyrode solutions. [Ca2+]i of glomus (type I cells) was assessed by superfusion techniques under identical conditions as for CSN recording experiments. The results indicate that 250 microM DNP increased [Ca2+]i of type I cells as well as CSN activity at both pHos, although alkalosis diminished these responses. Given that pHi will change with pHo, DNP did not make any additional pHi change, although [Ca2+]i changed. We conclude that DNP effects were due to [Ca2+]i change alone, and the relationship between [Ca2+]i and CSN activity are internally consistent.