CARDIAC-HYPERTROPHY AND TELEMETERED BLOOD-PRESSURE 6 WK AFTER BARORECEPTOR DENERVATION IN NORMOTENSIVE RATS

We investigated cardiac morphometry 6 wk after sinoaortic baroreceptor denervation (SAD) in Long-Evans rats. SAD (n = 19) was associated wit h an 11% increase in the weight of the left ventricle (LV) plus septum (P < 0.001) and a 39% increase in that of the right ventricular (RV) free wall (P < 0.001), relative to sham-operated rats (n = 18). RV wal l thickness was significantly increased in SAD animals, but there was no difference in the LV wall thickness and volumes of the RV and LV be tween groups. Constrictor responses to methoxamine and dilation respon ses to acetylcholine were assessed in an in vitro perfused mesenteric circulation preparation, but neither response was affected by SAD. Bar oreceptor denervation was associated with marked and significant incre ases in the variability (2.8-fold) and daily peak (39 mmHg) levels of telemetered mean arterial pressure (MAP) and small (5%) but significan t increases in the daily mean MAP level. Our results are consistent wi th an effect of increased MAP variability on ventricular weight but ca nnot rule out possible contributions from other mechanisms.