Intrathecal orexin A increases sympathetic outflow and respiratory drive, enhances baroreflex sensitivity and blocks the somato-sympathetic reflex.

ABSTRACT:

Background

Intrathecal (i.t.) injection of orexin A (OX-A) increases blood pressure and heart rate (HR), but the effects of OX-A on sympathetic and phrenic, nerve activity, and the baroreflex(es), somato-sympathetic and hypoxic chemoreflex(es) are unknown.

Experimental approach

Urethane-anaesthetized, vagotomized and artificially ventilated male Sprague-Dawley rats were examined in this study. The effects of i.t. OX-A (20 nmol 10 µL⁻¹) on cardiorespiratory parameters, and responses to stimulation of the sciatic nerve (electrical), arterial baroreceptors (phenylephrine hydrochloride, 0.01 mg kg⁻¹ i.v.) and peripheral (hypoxia) chemoreceptors were also investigated.

Key results

i.t. OX-A caused a prolonged dose-dependent sympathoexcitation, pressor response and tachycar

SUBMITTER: Shahid IZ 

PROVIDER: S-EPMC3042205 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature