title: Central venous pressure and plasma arginine vasopressin during water immersion in man.
abstract: The influence of increased central venous pressure (CVP) on the plasma concentration of arginine vasopressin (pAVP) was examined in 7 healthy males subjected to water immersion (WI) up to the neck following overnight food- and fluid restriction. During WI the subject sat upright in a pool (water temperature = 35.0 degrees C) for 6 h. In control experiments the subject assumed the same position outside the pool wearing a water perfused garment (water temperature = 34.6 degrees C). CVP increased markedly during WI and after 20 min of immersion it attained a level which was significantly higher than the control value (10.9 +/- 1.5 (mean +/- SE) vs. 2.2 +/- 1.3 mm Hg, p less than 0.01). This increase was sustained throughout the 6 h WI period. Simultaneously, after 20 min pAVP during WI was significantly lower than control values (1.8 +/- 0.3 vs. 2.2 +/- 0.3 pg X ml-1, p less than 0.05) and sustained throughout WI. Systolic arterial pressure increased significantly by 7-10 mm Hg (p less than 0.05) after 2 h of WI, while diastolic arterial pressure was unchanged. Heart rate was decreased by 10 bpm throughout immersion. There was no change in plasma osmolality when comparing control with immersion. A pronounced osmotic diuresis, natriuresis and kaliuresis occurred during WI, counteracting an acute significant increase in plasma volume of 6.5 +/- 1.9% (P less than 0.01 within 20 min of immersion). We conclude that an increase in CVP due to WI is accompanied by suppressed pAVP.
mesh_terms: D000328:Adult; D001127:Arginine Vasopressin / Q000097:blood*; D002496:Central Venous Pressure; D004231:Diuresis; D006339:Heart Rate; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007101:Immersion; D008297:Male; D009994:Osmolar Concentration; D010953:Plasma Volume; D013997:Time Factors; D014556:Urine / Q000502:physiology
chemical_list: D006454:Hemoglobins; D001127:Arginine Vasopressin