Rat tail suspension offers a useful model to reproduce physiologic responses to weightlessness.The present study was conducted in the head-down-tilt(HDT) rat model to assess changes in metabolism of body tissues emp...Rat tail suspension offers a useful model to reproduce physiologic responses to weightlessness.The present study was conducted in the head-down-tilt(HDT) rat model to assess changes in metabolism of body tissues employing 3H-nicotine. Twelve male rats were used in the study. Half of the rats were tail suspended at 30°for two weeks on a 12/12 light/dark cycle. During this period,body weight, food and fluid intakes were measured. At term, animals were anesthetized and injected IV withe a solution contaming 4 microuries of micotine. After 90 min the animals were sacrificed, exsanguinated and tissues (brain,blood,trachea,salivary gland,lung,heart,esophagus,spleen, kidneys and testes) were harvested. The distribution of 3H-nicotine per gram of each tissue was determinded and ealeulated as percent of total injected radioactivity. Final body weights of suspended ammals were significantly (P < 0.0 5) lower than those of eontrols(309±21 vs 350±11g). 3HNicotine waw retained in greatest amounts by the kindneys, followed inorder by salivary glands, spleen, and gastrointestinal tissues. compared to non-suspended control, the tissue retention of nicotine in suspended animals was decreased in the following tissues:esphyagus (25 %), aorta (25%). fundus (25%), trachea (22%), adrenals (18%), spleen (17 %), and pancreas (12 %). The decreased retention of mcotine in tissues from suspended animals may be indicative of the fluid shifts and changes in blood flow to those tissue beds. The lack of differnces in nicotine retention in liver and kidney between control and suspended groups may implicate a normal metabolic function of these organs even under simulated weightlessness.展开更多
文摘Rat tail suspension offers a useful model to reproduce physiologic responses to weightlessness.The present study was conducted in the head-down-tilt(HDT) rat model to assess changes in metabolism of body tissues employing 3H-nicotine. Twelve male rats were used in the study. Half of the rats were tail suspended at 30°for two weeks on a 12/12 light/dark cycle. During this period,body weight, food and fluid intakes were measured. At term, animals were anesthetized and injected IV withe a solution contaming 4 microuries of micotine. After 90 min the animals were sacrificed, exsanguinated and tissues (brain,blood,trachea,salivary gland,lung,heart,esophagus,spleen, kidneys and testes) were harvested. The distribution of 3H-nicotine per gram of each tissue was determinded and ealeulated as percent of total injected radioactivity. Final body weights of suspended ammals were significantly (P < 0.0 5) lower than those of eontrols(309±21 vs 350±11g). 3HNicotine waw retained in greatest amounts by the kindneys, followed inorder by salivary glands, spleen, and gastrointestinal tissues. compared to non-suspended control, the tissue retention of nicotine in suspended animals was decreased in the following tissues:esphyagus (25 %), aorta (25%). fundus (25%), trachea (22%), adrenals (18%), spleen (17 %), and pancreas (12 %). The decreased retention of mcotine in tissues from suspended animals may be indicative of the fluid shifts and changes in blood flow to those tissue beds. The lack of differnces in nicotine retention in liver and kidney between control and suspended groups may implicate a normal metabolic function of these organs even under simulated weightlessness.
