Fig. 5. Influence of short-term increase in MAP on mean heart rate (HR)–baroreflex sensitivity (slope) assessed by phenylephrine (PE, top ) and sodium nitroprusside (NP, bottom ) in six conscious rats. Blood pressure (BP) was increased with a low-dose infusion of PE (1.0–1.5 μg · kg−1· min−1) to match the BP elicited by bupivacaine 2 mg/kg at 1.5 min. Mean arterial pressure (MAP) increased from 118 ± 2 mmHg (basal) to 139 ± 2 mmHg (high), whereas HR decreased from basal 390 ± 7 to 302 ± 14 beat/min. Values represent mean ± SD.