ผลของยาไซโคลสปอรินเอต่อการทำหน้าที่ของตัวรับความดันเลือดแดง และหน้าที่ของไต เนื่องจากบทบาทของแองจิโอเท็นซินทู / สุรสีห์ อุ๋ยสุวรรณ = Effects of cyclosporin a (CsA) on baroreceptor reflex and renal function : role of angiotensin II / Surasee Ouisuwan
To investigate the effects of cyclosporin A (CsA) on baroreceptor reflex and renal function in 15 male dogs weighing 13-18 kg. The animals were divided into 3 groups and were treated orally as followed. Group 1 animals received enalapril at a dose of 0.5 mg/kg.bw./day for 10 days. Group 2 dogs received CsA at a dose of 20 mg/kg.bw./day for 7 days, while group 3 dogs received enalapril at the same dose as group 1 for 3 days and combined with CsA for 7 more days. Each experiment was performed on the day before and after receiving drugs, which represented the control and the post treatment values, respectively. Blood pressure and heart rate were recorded. Baroreceptor reflex was tested by either decreaing the blood pressure with sodium nitroprusside (SNP) or increasing with phenylephrine (PE). The relations between blood pressure and heart rate changes were recorded. Renal function was studied on the day after baroreflex testing. The results showed that in group 1, the diastolic blood pressure (DBP) decreasedsignificantly (p<0.05) while the heart rate (HR) was unaltered. In group 2, the mean arterial pressure (MAP), the systolic blood pressure (SBP), and the DBP increased significantly (p<0.05) while the HR was unaltered. In group 3, while the blood pressure remained unchanged, the HR decreased significantly (p<0.05). Study the baroreceptor reflex responses to the decrease or increase in blood pressure induced by SNP and PE, showed that dogs in group 1 had no changes in the set point and the sensitivity of the reflex. In group 2, the sensitivity response to the increased blood pressure decreased significantly (p<0.05) while the set point was unaltered. However, the baroreceptor reflex responses to the decreased blood pressure were not changed. There was no change in the baroreceptor reflex response to either the decrease or the increase of blood pressure in group 3. Study of renal function showed that in group1, the glomerular filtration rate (GFR), the effective renal blood flow (ERBF) and the effective renal plasma flow (ERPF) tended to decrease along with the slight decreases in the filtration fraction (FF) and the renal vascular resistance (RVR). In group 2, the RVR increased slightly, coincided with the decreases of the EFBF and the ERPF. As the GFR was unchanged, the FF tended to increase. In group 3, the GFR, the ERBF, and the ERBF, and the ERPF tended to increase as the RVR decreased. In this group, the urinary excretion of Na+ and C1- increased slightly, coincided with an increase in the free water excretion. In conclusion, CsA increased the SBP, the MAP and the DBP significantly. Enalapril would normalize the hypertensive effect of the CsA suggesting that the CsA may act via the renin-angiotensin system. The mechanism of CsA in inducing blood pressure elevation may in part, due to the impair baroreceptor reflex sensitivity when blood pressure was increased. The impaired baroreceptor reflex could be reversed by enalapril treatment.
