Breathing pattern during pharmacological activation and blockade of the intermediate area of the ventrolateral surface of the cat medulla

The present study analyzes the respiratory pattern of chloralose- (50-60 mg/kg,iv) anesthetized cats treated with Nembutal (NE) (30 mg/ml), glycine (GL) (200 mg/ml) or leptazol (LE) (200 mg/ml) topically applied to the intermediate area of the ventrolateral surface of the medulla oblongata in a volume of 20 micronl. Application of NE and GL produced a decrease in ventilation (-24%) and tidal volume (-25%) suggesting that the intermediate area facilitates respiratory drive and inhibits the inspiratory off-switch mechanism. These results are consistent with the view that intermediate area is necessary for the central chemosensitivity to CO2. The topical application of LE produced an increase in inspiration time (12.5%), expiration time (20.8%) and tidal volume (7%). The increased tidal volume caused by LE is compatible with it action as a GL antagonist

Effect of exercise training during pregnancy: maternal and fetal responses of the rat

Pregnancy duration, offspring number, body weight gain per day, as well as offspring body and heart weights were studied in pregnant Wistar rats subjected to exercise training at relative work loads of 60, 70, 80 or 90% of maximum oxygen consumption (VO2max) (N = 6 for each group). Pregnancy duration, offspring number and heart weight of the rats subjected to exercise during pregnancy were not different from the control group not subjected to exercise training. Body weight gain per day of pregnant rats subjected to exercise was 4.64 + or - 0.21, 4.79 + or - 0.12 g, respectively, for work loads of 70,80 or 90% of VO2max. This decrease of body weight gain per day was ignificantly different (P<0.05) from the control group (5.69 + or - 0.22 g). The offspring body weight decreased in the rats submitted to work loads of 70,80 and 90% of VO2max(5.3-0 + or - 0.02 and 5.24 + or - 0.01g, respectively) by comparison to the control group value (5.73 + or - 0.07 g). These results suggest that only intense exercise could impair body weight gain in pregnant rats and their offspring