Cardiorespiratory Responses to Acute Hypoxia and Hyperoxia in Adult and Neonatal Spontaneously Hypertensive and Normotensive Rats

The aim of this study was to investigate whether there are differences between particular characteristics of breathing regulation in primary hypertensive and normotensive states which might indicate significant differences in arterial chemoreceptor reflex function. Under air-breathing conditions, minute ventilation was similar in adult spontaneously hypertensive rats (SHR) (50 ± 2 ml/min x 100 g) and in Wistar-Kyoto rats (WKY) (54 ± 3 ml/min x 100 g) but significantly lower in randomly bred normotensive Wistar rats (NWR) (39 ± 1 ml/min x 100 g). In seven-day-old rats minute ventilation was 10.5 ± 1.2 ml/min x 10 g in SHR and 10.2 ± 1.4 ml/min x 10 g in WKY. Our data indicate that there is no elevation of the ventilatory drive under air-breathing conditions which can be unequivocally associated with primary hypertension in adult and neonatal animals. Acute inhibition of ventilation caused by hyperoxia indicated that oxygen dependent peripheral chemoreceptor activity during air-breathing was similar in SHR ...