Muscarinic acetylcholine receptors M₂ are upregulated in the atrioventricular nodal tract in horses with a high burden of second-degree atrioventricular block.

ABSTRACT:

Background

Second-degree atrioventricular (AV) block at rest is very common in horses. The underlying molecular mechanisms are unexplored, but commonly attributed to high vagal tone.

Aim

To assess whether AV block in horses is due to altered expression of the effectors of vagal signalling in the AV node, with specific emphasis on the muscarinic acetylcholine receptor (M₂) and the G protein-gated inwardly rectifying K⁺ (GIRK4) channel that mediates the cardiac I_K,ACh current.

Method

Eighteen horses with a low burden of second-degree AV block (median 8 block per 20 h, IQR: 32 per 20 h) were assigned to the control group, while 17 horses with a high burden of second-degree AV block (median: 408 block per 20 h, IQR: 1,436 per

SUBMITTER: Nissen SD 

PROVIDER: S-EPMC10687567 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature