CYCLOSPORINE-A IMPAIRS THE NOCTURNAL BLOOD-PRESSURE FALL IN RENAL-TRANSPLANT RECIPIENTS

In renal transplant recipients, hypertension and a diminished nocturna l blood pressure fall are frequently found. To investigate whether thi s diminished nocturnal blood pressure fall is related to the use of cy closporin A or to other factors, such as the use of glucocorticoids, w e measured 24-hour ambulatory blood pressure in 18 renal transplant re cipients both before and 16 weeks after conversion from cyclosporin A to azathioprine. Renal blood flow and glomerular filtration rate were estimated from I-131-hippurate and I-125-iothalamate clearances, respe ctively, and plasma concentrations of renin, atrial natriuretic peptid e, norepinephrine, prostaglandin E(2), and thromboxane B-2 were determ ined. During cyclosporin A treatment, mean 24-hour blood pressure was 117 +/- 3 mm Hg, and the nocturnal fall in blood pressure was 4 +/- 9 mm Hg. A nondipping diurnal blood pressure pattern was present in 13 p atients. After conversion to azathioprine, mean 24-hour blood pressure decreased to 109 +/- 3 mm Hg (P < .001), the nocturnal fall increased to 9 +/- 6 mm Hg, and the number of patients with a nondipping diurna l blood pressure pattern decreased to 9. The nocturnal fall in heart r ate (17 +/- 10 beats per minute) during cyclosporin A did not change a fter conversion. Body weight and plasma concentrations of norepinephri ne and renin did not change. Plasma concentrations of prostaglandin E( 2) and thromboxane B-2 decreased after conversion, as did plasma atria l natriuretic peptide. Renal blood flow and glomerular filtration rate increased after conversion. In conclusion, cyclosporin A appears to b e involved in the disturbance of the circadian blood pressure rhythm i n renal transplant recipients. Although the precise mechanism is uncle ar, the elevated plasma atrial natriuretic peptide and slightly suppre ssed plasma renin concentrations suggest that intravascular volume exp ansion may contribute to the observed hemodynamic alterations.