Does postsynaptic alpha 1-adrenergic receptor supersensitivity contribute to autonomic dysreflexia?
Quadriplegics often experience periods of severe hypertension known as autonomic dysreflexia. Clinically, these events have been well documented, but the mechanisms for mediating autonomic dysreflexia remain unclear. We used a chronic rat model to investigate the potential development of supersensitivity at postsynaptic alpha 1-adrenergic receptors as a contributing factor to the exaggerated sympathetic response characteristic of autonomic dysreflexia. Adult male Wistar and Sprague-Dawley rats were anesthetized and given spinal transection at T5. After 30 days, rats were reanesthetized and arterial and venous catheters implanted. Twenty-four hours later, colorectal distension (CRD) was used to evoke autonomic dysreflexia in conscious, spinalized rats. To gauge changes in alpha 1-receptor sensitivity, we assessed mean arterial pressure (MAP) in response to intravenous phenylephrine (PE) infusions. No consistent differences were observed between intact and spinalized rats. Therefore, sup
