UTERINE BLOOD FLOW AND RENAL SYMPATHETIC RESPONSES TO EXERCISE IN PREGNANT RABBITS

Abstract

We tested the hypothesis that pregnancy blunts the sympathetic and uterine blood flow (UtBF) responses to graded dynamic treadmill exercise in rabbits. A total of 10 term pregnant (P) and 6 nonpregnant (NP) rabbits were instrumented to measure renal sympathetic nerve activity (RSNA, N = 7 P, 6 NP) and left or right uterine artery blood flow (Transonic, N = 6 P, 3 NP). Rabbits were exercised for 5 min at 3 intensities (order alternated), each separated by > 45 min of rest: 7 m/min, 0% grade and 10 m/min at 6 and 17% grade. Only data from the highest exercise intensity are shown in the table.TableAt rest, pregnant rabbits had a lower blood pressure (BP), and higher, HR, UtBF and uterine conductance (UtC). In both groups, RSNA increased at the onset of exercise and remained elevated during steady-state (min 3–5) exercise, while UtBF decreased at the onset of exercise and returned to near-resting levels during min 3–5. Gestation-associated differences in absolute rest BP, UtBF and UtC were maintained at steady state exercise. There was no interaction between pregnancy status and exercise intensity in the RSNA or UtBF responses to steady-state exercise (min 3–5). At term pregnancy in rabbits, UtBF is well-maintained and the renal sympathoexcitatory response is preserved during short-term light to moderately heavy dynamic exercise.