Actas de congresos
Chronic phenytoin treatment increases basal ventilation but reduces peripheral ventilatory drive in the anesthetized rat
Fecha
2014Institución
Resumen
The hypoxic ventilatory response (HVR) in rats depends on the carotid body (CB) chemoreceptors. The acute blockage of the persistent Na+ current
(INaP) in rats reduces the CB chemosensory discharge, the basal ventilation and HVR. Because there is no data on the ventilatory effects of long term
INaP blockage we studied the ventilation in rats treated for 21 days with a INaP blocker. Male rats anesthetized with isofluorane 3 % in O2, received a
single dose of phenytoin (75 mg/kg, ip) and a daily dose provided by an osmotic pump (10 μg/day); sham rats received vehicle treatment. After 21 days,
rats were anesthetized with pentobarbitone (60 mg/kg); the femoral artery and trachea were cannulated and connected to a pressure transducer and a
pneumotacograph, respectively. Blood pressure and ventilatory signals were digitized and acquired at 10 kHz. Rats breathed air or different O2 contents
(FIO2; 0-100 %). Basal minute ventilation was significantly increased in treated (71.8 +/- 2.1 mL/min) with respect to sham (48.3 +/- 1.3mL/min) rats, by
a significant increase only in respiratory rate. On the other hand, in treated rats HRV to different FIO2 were consistently reduced to 19.9 +/- 2.5 % of
sham rat responses. Our results indicate that chronic phenytoin treatment reduces the peripheral ventilatory drive and modifies the respiratory rhythm,
suggesting an effect on the afferent activity and the central ventilatory rhythm generator.