Role of nitric oxide in rat locus coeruleus in hypoxia-induced hyperventilation and hypothermia

The locus coeruleus modulates the ventilatory and thermoregulatory response to hypoxia and contains nitric oxide synthase. Therefore, we examined the effects of L-NAME unilaterally microinjected into the locus coeruleus on hy poxic hyperventilation and hypothermia. Ventilation and body temperature we re measured before and after microinjection of L-NAME (100 nmol/0.5 mu l) i nto the locus coeruleus, followed by hypoxia. Control rats received microin jection of D-NAME (an inactive enantiomer of L-NAME). Under normoxia, L-NAM E treatment did not affect ventilation or body temperature. D-NAME did not affect hypoxia-induced hyperventilation and hypothermia. L-NAME treatment r educed the ventilatory response to hypoxia but did not affect hypoxia-induc ed hypothermia. These data suggest that nitric oxide in the locus coeruleus is involved in the ventilatory response to hypoxia, exercising an inhibito ry modulation on the locus coeruleus neurons, but plays no role in hypoxia- induced hypothermia. NeuroReport 11:2991-2995 (C) 2000 Lippincott Williams & Wilkins.