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

Thompson, Emma Louise (2013). Adrenaline increases ventilation via a β-receptor and carotid body-mediated mechanism: a role in the hyperventilation of hypoglycaemia? University of Birmingham. M.Res.

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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:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

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