The effect of chronic intermittent hypoxia to hypothalamus-pituitary-adrenal axis and growth hormone level in rats during sleep / 中国应用生理学杂志

<p><b>AIM</b>To research the effect of intermittent hypoxia during sleep on hypothalamus-pituitary-adrenal (HPA) axis and growth hormone (GH) level.</p><p><b>METHODS</b>Rats were respectively exposed to intermittent hypoxia, room air and continuous hypoxia, after 1 day, 3 days, 7 days and 30 days, mRNA levels of corticotropin-releasing hormone (CRH) and growth hormone releasing hormone (GHRH) in hypothalamus of rats were detected using RT-PCR, and the levels of CRH, GHRH, corticotropin(ACTH), cortex ketone, and growth hormone in plasma were measured.</p><p><b>RESULTS</b>After 30 days, the CRH mRNA levels in rats hypothalamus which exposed to intermittent hypoxia were increased significantly than those exposed to continuous hypoxia as well as normal control but GHRH decreased, there was no difference between continuous hypoxia and normal control. After 1 day, 3 days, and 7 days, there was no difference between continuous hypoxia and intermittent hypoxia. After 30 days, the plasmic level of CRH,ACTH and cortex ketone increased, GHRH decreased and GH had no obvious change.</p><p><b>CONCLUSION</b>The rats' HPA axis level increases and GHRH restrained with chronic intermittent hypoxia during sleep, feedback regulation disorders.</p>

Study of the mechanisms of dyspnea during exercise in COPD / 中国应用生理学杂志

<p><b>AIM</b>To study the relationships between dyspnea and respiratory drive or respiratory muscle function in COPD.</p><p><b>METHODS</b>Thirty-one patients with COPD and 26 normal subjects were involved in the study. Routine pulmonary function, pulmonary diffusing capacity, P0.1, PI(max) were measured at rest. Oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE) etc were observed during exercise test. Dyspnea was assessed with Borg Scale (BS) simultaneously. Arterial blood gas measured before and after exercise.</p><p><b>RESULTS</b>(1) PI(max) of COPD (5.33 +/- 1.95) kPa decreased compared with the normal subjects (7.02 +/- 2.53) kPa, P < 0.05, P0.1 of COPD (0.37 +/- 0.12) kPa increased compared with the normal subjects (0.26 +/- 0.09) kPa, P < 0.05, inspiratory drive efficacy (V(T)/P0.1) of COPD (1.6 +/- 0.31) L/kPa decreased than that of the normal subjects (2.1 +/- 0.53) L/kPa, P < 0.05. P0.1/PI(max) of COPD (0.069 +/- 0.021) was higher than that of the normal individuals (0.037 +/- 0.009), P < 0.01. (2) Peak exercise dyspnea was correlated with dyspnea at rest and P0.1/PI(max) (r = 0.41, P < 0.05 and r = 0.48, P < 0.05, respectively), and P0.1/PI(max) was also positively correlated with the change in BS from rest to maximal exercise (deltaBS) (r = 0.44, P < 0.05) in COPD patients.</p><p><b>CONCLUSION</b>In COPD, breathlessness during exercise is not simply related to hyperinflation and the damaged gas exchange, but also to the relatively increased respiratory drive and dysfunction of respiratory muscle.</p>