ABSTRACT
Acute and chronic hypoxia influence blood glucose levels and decrease body weight. Ghrelin increases appetite and body weight and regulates energy metabolism and also glucose homeostasis. Therefore, in the present study the effects of ghrelin administration on blood glucose, body weight, food intake and hematocrit were investigated in a model of systemic normobaric acute and chronic hypoxia in adult male rats. Forty-eight adult male Wistar rats were divided into six groups [acute control + saline, chronic control + saline, acute or chronic hypoxia + saline, acute or chronic hypoxia + ghrelin [80 microg/kg/day, ip]]. Control groups remained in room air [21% O[2]] and hypoxia [11% O[2]] induced by a normobaric hypoxic chamber for two days [acute] or ten days [chronic]. Blood glucose levels, body weight, food intake and hematocrit were assessed. Chronic hypoxia caused a significant [P<0.001] decrease in blood glucose levels. Administration of ghrelin increased blood glucose levels significantly in acute [P<0.05] and chronic [P<0.01] hypoxia. Body weight decreased [P<0.001] in both acute and chronic hypoxic groups. Administration of ghrelin could [P<0.001] prevent decrease in body weight in chronic hypoxia group. Acute and chronic [P<0.001] hypoxia significantly decreased food intake. Ghrelin however increased food intake in both the acute [P<0.001] and chronic [P<0.05] hypoxia groups. Acute [P<0.01] and chronic [P<0.001] hypoxia also increased hematocrit. Ghrelin administration is useful in modulating blood glucose, body weight and food intake in hypoxic situations
ABSTRACT
Breathing through the nose and mouth is one of the controversial issues during exercise. The present study was scheduled to investigate a quantitative approach to habitual versus the obligatory switching point from nasal to oronasal breathing during exercise as well as coincidence of soft palate movement as the main aims of this study, that has not been studied previously. In this experimental study, twenty-five young adult volunteers [12 males and 13 females] participated in the study. An incremental exercise protocol was incorporated in three protocols for determination of switching point from nasal to oronasal breathing during habitual, obligatory conditions, and determination of change in soft palate position. In two latter conditions, subjects were advised to breathe via nasal route as long as they could. Switching point from nasal to oronasal breathing was determined by a CO2 sensor. Duration of habitual nasal breathing was shorter than tolerated nasal breathing. Obligatory opening of mouth and change in soft palate position were coincident. Ventilation increment at habitual shift from nasal to oronasal respiration was lower than obligatory one. Switching time to oronasal breathing correlated either with ventilation increment or exercise workload. Rate of ventilation was higher in females but switching time was significantly longer in males in three mentioned conditions. In the last two protocols, ventilation incrimination was significantly lower in females. In conclusion, duration of tolerated nasal breathing was longer than habitual one and changes in the position of soft palate occurs simultaneously
Subject(s)
Humans , Male , Female , Mouth Breathing , Palate, Soft , Exercise Test , ExerciseABSTRACT
The purpose of this study was to investigate the effect of exercise and post dehydration water drinking on variations in plasma arginine vasopressin [PAVP], plasma osmolality [Posm] and tympanic temperature [Ttym] in healthy males. Eight healthy young males [27.4 +/- 0.8 yrs old] volunteered for the study. They performed constant work exercise, at a rate of 60 rpm at 50% of individual work load for VO2 peak for 30 minutes. Six blood samples [at minutes 0, 15 and 30 during exercise and at minutes 3, 15 and 30 after termination of exercise] were obtained through an indwelling venous cannula. Plasma concentrations for Na+, and AVP were determined. Posm was calculated using Na+ concentrations. Simultaneous variations in Ttym were also determined. Our results demonstrated a positive correlation between increase in PAVP and both Posm and Ttym during exercise but not during the recovery period. When exercise was combined with water drinking a fast and significant suppression in PAVP occurred [P<0.05]. These results suggest that Posm and Ttym have no significant effect on AVP secretion post exercise, and thus other factors must be involved in AVP secretion during post exercise recovery period