Peripheral mechanisms involved in autonomic hyperreflexia

Funded Activity Summary

Bladder distension or minor unheeded injuries below the lesion in spinally injured people often lead to episodes of high blood pressure that may cause stroke or death. These events require emergency hospitalization and are expensive as well as dangerous. After spinal injury, the control of sympathetic nerves that supply arteries and regulate blood pressure is lost. However, the nerves below the injury remain in place and the spinal cord below the lesion contains connections that can activate them. Signals from the bladder or skin enter the remaining lower part of the spinal cord and activate the sympathetic supply generating a rise in blood pressure. This project will test the hypothesis that increased sensitivity of arteries to the chemicals released from the sympathetic nerves leads to excessive vessel constriction, contributing to the exaggerated increase in pressure. We will investigate arteries removed from rats with experimental spinal transection. We will test the contractions of the arteries (a) to sympathetic nerve stimulation and (b) to the chemicals noradrenaline, adenosine 5'-triphosphate (ATP) and neuropeptide Y that are normally released during nerve activity. We will determine whether release of noradrenaline and ATP from nerves is normal or augmented using electrochemical and electrophysiological techniques. We will compare the responses with those in normal arteries, those in arteries whose nerves have been silenced by removing all connections from the spinal cord and those in arteries that have lost all their nerve supply. This will enable us to identify whether the mechanisms for release of transmitter substances are modified and whether the arterial muscle is hypersensitive to these substances. The results will help in the design of safer treatment for these potentially lethal emergencies in spinal patients.

Funded Activity Details

Start Date: 01-01-2002

End Date: 01-01-2004

Funding Scheme: NHMRC Project Grants

Funding Amount: $229,917.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Medical bacteriology

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Autonomic nervous system disease | Control of blood pressure | Neurovascular mechanism | Spinal cord injury | Sympathetic nervous system | Vascular reactivity | Vascular smooth muscle

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