Castellani J W, Maresh C M, Armstrong L E, Kenefick R W, Riebe D, Echegaray M, Kavouras S, Castracane V D
Department of Sport, Leisure, and Exercise Science, University of Connecticut, Storrs, USA.
Eur J Appl Physiol Occup Physiol. 1998 Feb;77(3):242-8. doi: 10.1007/s004210050328.
Exercise following exercise-induced dehydration (EID) has been shown to elevate concentrations of plasma norepinephrine (NE) and hypothalamic-pituitary-adrenal axis hormones. However, it is not known how intravenous (i.v.) rehydration (Rh) with isotonic (ISO) or hypotonic (HYPO) saline affects these hormone concentrations. It was hypothesized that HYPO, versus ISO, would lead to lower plasma NE and cortisol concentrations ([CORT]) during subsequent exercise following EID due to a decrease in plasma sodium concentration [Na+]. Eight non-heat acclimated men completed three experimental treatments (counterbalanced design) immediately following EID (33 degrees C) to -4% body mass loss. The Rh treatments were i.v. 0.9% NaCl (ISO, 25 ml x kg[-1]), i.v. 0.45% NaCl (HYPO, 25 ml x kg[-1]), and no fluid (NF). After Rh and rest (2 h total), the subjects walked at 53-54 percent of maximal O2 uptake for 45 min at 36 degrees C. After Rh, the following observations were made before/during exercise: percentage change in plasma volume (PV) was lower in NF compared to ISO and HYPO but similar between ISO and HYPO; delta[Na+] was similar between ISO and NF and higher in ISO compared to HYPO; delta plasma NE was higher in NF compared to ISO and HYPO, but similar between ISO and HYPO; delta plasma [CORT] was higher in NF compared to ISO and HYPO and higher in ISO compared to HYPO; rectal temperature was higher in NF compared to ISO and HYPO. These data would suggest that sympathetic nervous activity and [CORT] during exercise, subsequent to EID and Rh, was affected by lower PV (probably through cardiopulmonary baroreflexes) as well as core temperature. Furthermore, [CORT] was affected by delta[Na+] after Rh through an unknown mechanism.
运动诱导脱水（EID）后进行运动已被证明会提高血浆去甲肾上腺素（NE）和下丘脑 - 垂体 - 肾上腺轴激素的浓度。然而，尚不清楚用等渗（ISO）或低渗（HYPO）盐水进行静脉（i.v.）补液（Rh）如何影响这些激素浓度。据推测，与ISO相比，HYPO会导致EID后随后运动期间血浆NE和皮质醇浓度（[CORT]）降低，原因是血浆钠浓度[Na +]降低。八名未进行热适应的男性在EID（33摄氏度）导致体重减轻4%后立即完成了三种实验处理（平衡设计）。Rh处理分别为静脉注射0.9%氯化钠（ISO，25 ml·kg[-1]）、静脉注射0.45%氯化钠（HYPO，25 ml·kg[-1]）和不补液（NF）。在Rh和休息（共2小时）后，受试者在36摄氏度下以最大摄氧量的53 - 54%步行45分钟。Rh后，在运动前/运动期间进行了以下观察：与ISO和HYPO相比，NF组的血浆容量（PV）百分比变化较低，但ISO和HYPO组之间相似；ISO和NF组之间的δ[Na +]相似，且ISO组高于HYPO组；与ISO和HYPO相比，NF组的δ血浆NE较高，但ISO和HYPO组之间相似；与ISO和HYPO相比，NF组的δ血浆[CORT]较高，且ISO组高于HYPO组；与ISO和HYPO相比，NF组的直肠温度较高。这些数据表明，EID和Rh后运动期间的交感神经活动和[CORT]受较低的PV（可能通过心肺压力反射）以及核心温度的影响。此外，Rh后[CORT]受δ[Na +]影响，但其机制尚不清楚。
