Norepinephrine-induced pulmonary petechiae in the rat: an experimental model with potential implications for sudden infant death syndrome.

Autonomic nervous system abnormalities have been implicated in infants dying of or considered at high risk of sudden infant death syndrome (SIDS). In a rat model, norepinephrine (0.02 mg/kg) caused systemic hypertension and numerous pulmonary petechiae, the latter a common finding in SIDS. Petechiae were not seen below the diaphragm. The animals were killed by tracheal occlusion 5 min after the intravenous administration of norepinephrine. The number of pulmonary petechiae was greatly reduced by alpha-adrenergic blockade (phentolamine) and dopaminergic blockade (haloperidol) but not by beta-adrenergic blockade (timolol). A significantly greater reduction of peak mean systemic arterial pressure occurred after alpha-adrenergic blockade than with other blocking agents. It is conceivable that hypoxia-induced endogenous catecholamine release contributes to the pathogenesis of pulmonary petechiae found at necropsy of SIDS victims.