Nowicki M, Fliser D, Fode P, Ritz E
Department of Internal Medicine, Ruperto-Carola University, Heidelberg, Germany.
J Clin Endocrinol Metab. 1996 Jan;81(1):156-9. doi: 10.1210/jcem.81.1.8550745.
The euglycemic clamp technique is a useful tool to evaluate insulin-mediated glucose uptake. The plasma phosphate concentration decreases during euglycemic clamp studies. Because insulin-dependent glucose uptake is closely related to phosphate uptake, we investigated whether modulation of plasma phosphate levels in the range observed during clamp studies influences insulin sensitivity. We studied 11 healthy (phosphate-replete) male volunteers (mean age, 27.5 +/- 1.8 yr;, mean body mass index, 23.9 +/- 1.6 kg/m2) in a double blind placebo-controlled cross-over study. The volunteers received in random order on two occasions either an infusion of sodium chloride (sham infusion) or an infusion of sodium phosphate. Insulin sensitivity was assessed under euglycemic conditions (clamp technique). The mean plasma phosphate concentration decreased with sham infusion from 1.09 +/- 0.17 to 0.64 +/- 0.13 mmol/L, whereas it increased with phosphate infusion from 1.06 +/- 0.19 to 1.32 +/- 0.13 mmol/L. In all volunteers except one the glucose disposal rate (M-value) was higher after phosphate infusion (mean M-value, 10.4 +/- 1.5 mg/kg.min) than that after sham infusion (mean M-value, 9.4 +/- 1.5 mg/kg.min; P < 0.01, by Wilcoxon's test for paired samples). There were no significant differences in mean plasma glucose, sodium, insulin, or arterialized standard bicarbonate levels with the two infusion protocols. Mean plasma calcium, albumin-corrected calcium, and potassium levels, however, were all significantly (P < 0.05) lower after phosphate infusion than after sham infusion. The mean PTH level decreased with sham infusion from 28 +/- 9 to 20 +/- 6 ng/L, whereas it increased with phosphate infusion from 26 +/- 9 to 36 +/- 8 ng/L, whereas it increased with phosphate infusion from 26 +/- 9 to 36 +/- 8 ng/L. The difference between the two infusion protocols was statistically significant (P < 0.01). The data presented illustrate that plasma phosphate (and calcium) levels may be confounders that should be at least monitored, and possibly controlled for, when performing euglycemic clamp studies.
正常血糖钳夹技术是评估胰岛素介导的葡萄糖摄取的一种有用工具。在正常血糖钳夹研究期间，血浆磷酸盐浓度会降低。由于胰岛素依赖的葡萄糖摄取与磷酸盐摄取密切相关，我们研究了在钳夹研究期间观察到的血浆磷酸盐水平范围内的调节是否会影响胰岛素敏感性。我们在一项双盲安慰剂对照的交叉研究中，对11名健康（磷酸盐充足）的男性志愿者（平均年龄27.5±1.8岁；平均体重指数23.9±1.6kg/m²）进行了研究。志愿者在两个时间段随机接受输注氯化钠（假输注）或输注磷酸钠。在正常血糖条件下（钳夹技术）评估胰岛素敏感性。假输注时，平均血浆磷酸盐浓度从1.09±0.17mmol/L降至0.64±0.13mmol/L，而输注磷酸盐时，其从1.06±0.19mmol/L升至1.32±0.13mmol/L。除一名志愿者外，所有志愿者在输注磷酸盐后的葡萄糖处置率（M值）（平均M值为10.4±1.5mg/kg·min）高于假输注后（平均M值为9.4±1.5mg/kg·min；通过配对样本的Wilcoxon检验，P<0.01）。两种输注方案在平均血浆葡萄糖、钠、胰岛素或动脉化标准碳酸氢盐水平上无显著差异。然而，输注磷酸盐后的平均血浆钙、白蛋白校正钙和钾水平均显著低于假输注后（P<0.05）。假输注时，平均甲状旁腺激素水平从28±9降至至20±6ng/L，而输注磷酸盐时，其从26±9升至36±8ng/L。两种输注方案之间的差异具有统计学意义（P<0.01）。所呈现的数据表明，在进行正常血糖钳夹研究时，血浆磷酸盐（和钙）水平可能是混杂因素，至少应进行监测，并且可能需要加以控制。
