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Adrenaline increases ventilation via a β-receptor and carotid body-mediated mechanism: a role in the hyperventilation of hypoglycaemia?

Thompson, Emma Louise (2013)
M.Res. thesis, University of Birmingham.

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Abstract

A role for the carotid body (CB) in glucoregulation has been proposed but the evidence is conflicting. Hypoglycaemia in vivo induces a CB-dependent hyperventilation, but it is not agreed whether this reflects a direct action of reduced blood glucose on the CB, or an indirect effect of adrenaline. We therefore investigated the effects of adrenaline and hypoglycaemia upon ventilation.
Ventilation (V\(_E\)) was recorded during infusions of adrenaline or insulin (to induce hypoglycaemia) in anaesthetized male Wistar rats. CB-mediated effects were determined by application of hyperoxia at each dose. This was repeated during propranolol infusion. Hypercapnia was applied at control and at the end of adrenaline or insulin infusion.
Adrenaline and hypoglycaemia evoked increases in V\(_E\), without an associated change in P\(_a\)CO\(_2\). Hyperoxia reduced baseline V\(_E\) and offset the ventilatory responses. Propranolol reduced baseline V\(_E\) and abolished the hypoglycaemia-mediated ventilatory increase, but an increased P\(_a\)CO\(_2\) occurred. Both hypoglycaemia and adrenaline increased the hypercapnic ventilatory response, which was blocked by propranolol.
These data suggest that adrenaline may underlie the increased V\(_E\) seen in hypoglycaemia via a β-mediated, O\(_2\) independent pathway within the CB. It also suggests that the increased V\(_E\) during hypoglycaemia is a hyperpnoea that is appropriate to the increased metabolism.

Type of Work:M.Res. thesis.
Supervisor(s):Kumar, Prem and Coney, Andrew
School/Faculty:Colleges (2008 onwards) > College of Medical & Dental Sciences
Department:School of Clinical and Experimental Medicine
Subjects:QH301 Biology
RC Internal medicine
Institution:University of Birmingham
ID Code:3692
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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