高血圧合併2型糖尿病患者における局所運動筋酸素動態に関する検討

本研究は,2型糖尿病患者を高血圧合併の有無により分類し,運動筋酸素動態の差異を明らかにすることを目的とした.運動は,最大随意筋力の30%の強度にて3分30秒間の足関節底屈運動を行い,終了直前30秒間に一時的動脈血流遮断法を併用して,筋酸素利用変化率(%MO2)を算出し,運動終了後の筋酸素化レベル回復時間(TR)を測定した.その結果,高血圧合併2型糖尿病患者は,ヘモグロビンA1cおよび上腕動脈-足動脈間脈波伝播速度(baPWV)が有意に高値を示し(p<0.05),%MO2 に有意差は認められなかった.またTRは有意に延長し(p<0.05),baPWVとTRには有意な正の相関関係を認めた(r=0.58,p<0.05).以上のことから,高血圧合併2型糖尿病患者では,高血圧を合併しない糖尿病患者と比較して,中等度運動での筋酸素化レベルに差異は認められないが,動脈硬化により酸素供給が低下した結果,TRが延長することが明らかとなった.

Background : It is known that hypertension with type 2 diabetes mellitus increases the risk of arterial stiffness, but it is not clear whether it is accompanied by abnormal oxygenation in the exercising muscle. Methods and results: A total of 50 patients with type 2 diabetes, comprising normotensive patients (n=34, Age:53.6±8.6, BMI:23.0±3.9) and hypertensive patients (n=16, Age:53.9±8.2, BMI:24.5±3.5) , was studied. Right gastronomies muscle oxygenation was measured using near-infrared spectroscopy while resting and in a 210 sec planter flexion exercise. Muscle oxygen utilization rate (%MO2) was calculated as the increasing rate of oxygenated hemoglobin/mymoglobin during a 30 sec arterial occlusion, and reoxygenation time (TR) was calculated after arterial occlusion. The results demonstrated that glycol hemoglobin A1c (HbA1c) and baPWV in hypertensive patients (HbA1c:7.5±1.2%, baPWV:1777.9±320.7 cm/sec) were significantly different from those in normotensive patients (HbA1c:6.7±0.8%, baPWV:1520.2±211.8 cm/sec)(p<0.05, p<0.001), while no difference was observed in %MO2. Moreover, the TR was found to be slower in the hypertensive patients, and showed a positive relationship with the baPWV (r=0.58, p<0.05). From these results, it could be concluded that the arterial stiffness was caused by the decrease of oxygenation and the prolonging of TR in the hypertension with type 2 diabetes patients.