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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Baroreflex, Blood Pressure, Bradycardia, Carbon Dioxide, Dose-Response Relationship, Drug, Electrocardiography, Heart Rate, Hypotension, Injections, Spinal, Male, Neurotensin, Phrenic Nerve, Rats, Rats, Sprague-Dawley, Spinal Cord, Splanchnic Nerves.
user
Is intrathecal neurotensin hypotensive , sympathoinhibitory and enhances the baroreflex in anaesthetized rat? Context: The neuromodulatory effects of the gut-neuropeptide neurotensin on sympathetic vasomotor tone, central respiratory drive and adaptive reflexes in the spinal cord, are not known. Neurotensin (0.5 µM-3 mM) was administered into the intrathecal (i.t.) space at the sixth thoracic spinal cord segment in urethane-anaesthetized, paralysed, vagotomized male Sprague-Dawley rats. Pulsatile arterial pressure, splanchnic sympathetic nerve activity (sSNA), phrenic nerve activity, ECG and end-tidal CO(2) were recorded. Neurotensin caused a dose-related hypotension, sympathoinhibition and bradycardia. The maximum effects were observed at 3000 µM, where the decreases in mean arterial pressure (MAP), heart rate (HR) and sSNA reached -25 mmHg, -26 beats min(-1) and -26% from baseline, respectively. The sympathetic baroreflex was enhanced. Changes in central respiratory drive were characterized by a fall in the amplitude of the phrenic nerve activity. Finally, administration of SR 142948A (5 mM), a potent, selective antagonist at neurotensin receptors, caused a potent hypotension (-35 mmHg), bradycardia (-54 beats min(-1) ) and sympathoinhibition (-44%). A reduction in the amplitude and frequency of the phrenic nerve activity was also observed.
assistant
The data demonstrate that neurotensin plays an important role in the regulation of spinal cardiovascular function, affecting both tone and adaptive reflexes. Final Decision: yes