Musabayane C T, Ndhlovu C E, Balment R J
Department of Physiology, University of Zimbabwe, Mount Pleasant, Harare.
Ren Fail. 1995 Mar;17(2):107-16. doi: 10.3109/08860229509026247.
Male Sprague-Dawley rats (300-400 g) were made diabetic by an i.p. injection of streptozotocin (STZ, 60 mg/kg in citrate buffer, n = 8) to examine renal function in well-established diabetes mellitus. Vehicle-injected animals (n = 8) acted as controls. The mean weekly total amounts of food taken by control and STZ-diabetic rats did not differ, but diabetic rats exhibited diarrhea and drank more water. STZ-diabetic rats progressively lost weight from the first to the third week but gained weight in the fourth week. At 5 weeks the weight stabilized, plasma glucose concentration was elevated, and this was associated with increased kidney weight. The weekly urine volume from STZ-diabetic rats was elevated throughout the 5-week period of study and this was associated with significantly lower urinary outputs of Na+ and higher outputs of K+ than those of control animals. After 5 weeks of STZ diabetes, plasma corticosterone and aldosterone concentrations in unanesthetized rats did not differ significantly from values seen in controls. To examine renal function in more detail, groups of Inactin-anesthetized 5-week STZ-diabetic rats (n = 7) and control rats (n = 7) were placed on continuous jugular infusion of 0.077 M NaCl at 150 microL/min for 8.5 h. Following a 3.5-h equilibration period, urine flow and Na+, K+, and Cl- outputs were determined for the subsequent 5-h period, with mean arterial pressure and glomerular filtration rate (GFR). STZ-diabetic rats voided significantly less of the infused fluid and the urinary excretions of Na+ and K+ were lower than those of controls. Mean arterial blood pressure and GFR values in STZ-diabetic rats did not differ statistically from those seen in controls. Following hypotonic saline infusion for 8.5 h the levels of aldosterone were elevated significantly (p < 0.01) in STZ-diabetic rats by comparison with control animals (5.36 +/- 1.58 nmol/L, n = 7 vs. 2.36 +/- 0.12 nmol/L, n = 7). It is concluded that a challenge of hypotonic saline load to rats with 5 weeks of STZ diabetes mellitus elevates plasma aldosterone to reduce the ability to excrete Na+.
通过腹腔注射链脲佐菌素（STZ，在柠檬酸盐缓冲液中60毫克/千克，n = 8）使雄性Sprague-Dawley大鼠（300 - 400克）患糖尿病，以研究已确诊糖尿病中的肾功能。注射溶媒的动物（n = 8）作为对照。对照大鼠和STZ诱导的糖尿病大鼠每周摄入的食物总量均值无差异，但糖尿病大鼠出现腹泻且饮水更多。STZ诱导的糖尿病大鼠从第一周到第三周体重逐渐减轻，但在第四周体重增加。在5周时体重稳定，血浆葡萄糖浓度升高，且这与肾脏重量增加相关。在为期5周的研究期间，STZ诱导的糖尿病大鼠每周尿量均升高，且与对照动物相比，其尿钠排出量显著降低，尿钾排出量升高。STZ诱导糖尿病5周后，未麻醉大鼠的血浆皮质酮和醛固酮浓度与对照值无显著差异。为更详细地研究肾功能，将戊巴比妥麻醉的5周龄STZ诱导的糖尿病大鼠组（n = 7）和对照组大鼠（n = 7）以150微升/分钟的速度持续颈静脉输注0.077 M NaCl，持续8.5小时。在3.5小时的平衡期后，在随后的5小时内测定尿流量以及钠、钾和氯的排出量，并同时测定平均动脉压和肾小球滤过率（GFR）。STZ诱导的糖尿病大鼠排出的输注液体明显较少，尿钠和尿钾排泄量低于对照组。STZ诱导的糖尿病大鼠的平均动脉血压和GFR值与对照组相比无统计学差异。与对照动物（2.36±0.12纳摩尔/升，n = 7）相比，在8.5小时的低渗盐水输注后，STZ诱导的糖尿病大鼠的醛固酮水平显著升高（p < 0.01）（5.36±1.58纳摩尔/升，n = 7）。得出的结论是，对患STZ糖尿病5周的大鼠进行低渗盐水负荷刺激会使血浆醛固酮升高，从而降低排钠能力。
