Exaggerated Cardiovascular Stress Responses and Impaired β-Adrenergic–Mediated Pressor Recovery in Obese Zucker Rats

Clinical studies have demonstrated that the pressor response to acute stress is larger in obese versus lean individuals. We therefore tested the hypotheses that the pressor response to behavioral stress is greater in obese (OZRs) versus lean Zucker rats (LZRs) and that reduced β-adrenergic–mediated vasodilation contributes to the enhanced pressor response. Animals were restrained and subjected to acute pulsatile air jet stress (3 minutes), followed by a poststress period of 20 minutes; β-adrenergic blockade was achieved with propranolol (5 mg/kg, IV) given 15 minutes before the start of air jet stress. Mean arterial pressure (MAP) was continuously monitored by telemetry. Untreated OZRs responded with a greater integrated pressor response (area under the curve [AUC]) to acute stress (41.2±6.1 versus 21.2±3.3 mm Hg×3 minutes, OZR versus LZR; P P