Obesity related pathologies are the health care crisis of our generation. The fat cell derived
adipokine leptin has been shown to be a
central stimulant of respiration. Very high levels of
leptin, however, are associated with the depressed ventilatory phenotype observed in
obesity hypoventilation syndrome.
Leptin receptors have been identified on carotid body type I cells but how their activation might influence the physiology of these cells is not known.The acute application of
leptin evoked calcium signaling responses in isolated type I cells. Cells increased their
Fura 2 ratio by 0.074 ± 0.010 ratio units (n = 39, P < 0.001).
Leptin also increased the peak membrane currents in 6 of 9 cells increasing the peak macroscopic currents at +10 mV by 61 ± 14 % (p < 0.02).
Leptin administered in the presence of the selective BK(Ca) channel inhibitor
Paxilline (0.5 μM) failed to increase membrane currents (n = 5). Interestingly,
leptin did not significantly alter the resting membrane potential of isolated type I cells (n = 9) and anoxic/acidic depolarizations were unaffected by
leptin (n = 7, n = 6).These data suggest that
leptin receptors are functional in type I cells but that their acute activation does not alter chemosensory properties. Future studies will use chronic models of
leptin dysregulation.