Cyclosporine A modulates baroreceptor function in kidney transplant recipients

Cyclosporine has been described to increase the sympathetic tone. Alteratio ns in sympathetic tone may contribute to baroreceptor dysfunction. Therefor e, in this study baroreceptor function in 20 kidney transplant recipients w as investigated under both low and high cyclosporine whole blood concentrat ions using the sequence analysis technique. The sympathetic nerve activity was estimated by calculating the low frequency oscillation of heart rate an d blood pressure following Fast Fourier Transformation (FFT). Besides cyclo sporine, azathioprine and prednisolone no other drugs were used. The increa se in cyclosporine whole blood levels (from 101+/-13.4 ng/ml to 469+/-52 ng /ml) did not change mean arterial blood pressure significantly (83.7+/-2.5 vs. 82.2+/-2.0 mmHg). Baroreflex sensitivity in +PI/+RR (+pulsinterval/+blo od pressure) sequences, however, increased from 11.2+/-0.4 to 13.0+/-0.5 ms /mmHg, whereas it was reduced in -PI/-RR (-pulsinterval/-blood pressure) se quences (14.4+/-0.3 to 12.5+/-1.1 ms/mmHg). The increase in cyclosporine wh ole blood concentrations was associated with an increase in low frequency o scillation of heart rate (430+/-12 to 461+/-13) and blood pressure (452+/-9 to 469+/-12), indicating an enhanced sympathetic tone. Our results provide evidence that cyclosporine A by itself alters baroreceptor function. An im balance between the sympathetic and parasympathetic nervous system due to a n enhanced sympathetic tone may explain the reduction in -PI/-RR and the in crease in +PI/+RR sequence baroreflex sensitivity. (C) 1999 Elsevier Scienc e Ireland Ltd. All rights reserved.