College of Medicine of University of Lagos,Department of Physiology,Room020,.
.
Niger J Physiol Sci. 2021 Dec 31;36(2):149-157. doi: 10.54548/njps.v36i2.2.
Plasma osmolality (pOsmol) and neurohumoral signals play important roles in the pathophysiology of cardiovascular diseases. Our study investigated the effect of high environmental temperature (HET) on neurohumoral responses and pOsmol in rats fed a high salt diet (HSD), with and without angiotensin II receptor blockade (ARB), using telmisartan. Fifty-six male 8-week old Sprague-Dawley rats (95-110g) were randomly assigned into seven groups of 8 rats. These included control rats (I) fed with 0.3% NaCl diet (normal diet, ND); salt-loaded rats (II) fed with 8% NaCl (high salt) diet; ND rats (III) exposed to HET (38.5±0.5oC ) 4 hours daily per week; rats (IV) fed with 8% NaCl diet and exposed to HET daily. Others included rats (V) fed with 8% NaCl diet and treated with telmisartan (30mg/kg); ND rats (VI) exposed to HET and treated with telmisartan; rats (VI) fed with 8% NaCl diet, exposed to HET and treated with telmisartan. Plasma angiotensin II, aldosterone, vasopressin and norepinephrine (NE) concentrations were determined by ELISA technique; pOsmol from plasma K+, Na+ and Urea. HSD combined with HET in rats synergistically increased pOsmol (P<0.001) with an associated non-synergistic rise in fluid intake (P<0.001), fluid balance (P<0.001), plasma angiotensin II (P<0.01) and aldosterone (P<0.05), NE (P<0.001) and vasopressin (P<0.05) concentrations compared to control. Telmisartan did not alter pOsmol in all the treated-rats, but normalized fluid intake levels and plasma vasopressin in the rats exposed to either HSD or HEt alone. Prolonged exposure of rats to hot environment exacerbated the effect of excess dietary salt on pOsmol, with no effect on angiotensin II-mediated neurohumoral responses.
血浆渗透压（pOsmol）和神经激素信号在心血管疾病的病理生理学中发挥着重要作用。我们的研究调查了高环境温度（HET）对接受高盐饮食（HSD）的大鼠神经激素反应和 pOsmol 的影响，同时使用替米沙坦阻断血管紧张素 II 受体（ARB）。56 只 8 周龄雄性 Sprague-Dawley 大鼠（95-110g）随机分为 7 组，每组 8 只。包括对照组（I）给予 0.3%NaCl 饮食（正常饮食，ND）；盐负荷组（II）给予 8%NaCl 饮食（高盐）；ND 组（III）每周每天暴露于 HET（38.5±0.5°C）4 小时；给予 8%NaCl 饮食并每天暴露于 HET 的大鼠（IV）；给予 8%NaCl 饮食并给予替米沙坦（30mg/kg）的大鼠（V）；暴露于 HET 并给予替米沙坦的 ND 大鼠（VI）；给予 8%NaCl 饮食、暴露于 HET 并给予替米沙坦的大鼠（VI）。通过 ELISA 技术测定血浆血管紧张素 II、醛固酮、血管加压素和去甲肾上腺素（NE）浓度；从血浆 K+、Na+和 Urea 中测定 pOsmol。HSD 与 HET 联合作用于大鼠，协同性地增加了 pOsmol（P<0.001），同时非协同性地增加了液体摄入（P<0.001）、液体平衡（P<0.001）、血浆血管紧张素 II（P<0.01）和醛固酮（P<0.05）、NE（P<0.001）和血管加压素（P<0.05）浓度与对照组相比。替米沙坦没有改变所有治疗组大鼠的 pOsmol，但使暴露于单独 HSD 或 HET 的大鼠的液体摄入水平和血浆血管加压素正常化。大鼠长时间暴露于热环境会加剧过量膳食盐对 pOsmol 的影响，对血管紧张素 II 介导的神经激素反应没有影响。
