Electrophysiological characterisation of atrial volume receptors using ex‐vivo models of isolated rat cardiac atria

Campbell, T.; Shenton, F.C.; Lucking, E.; Pyner, S.; Jones, J.F.X.

Abstract

Atrial volume receptors are a family of afferent neurons whose mechanically sensitive endings terminate in the atria, particularly at the cavo‐atrial junctions. These mechanosensors form the afferent limb of an atrial volume receptor reflex which regulates plasma volume. The prevailing functional classification of atrial receptors arose as a result of in‐vivo recordings in the cat and dog and were classified as type A, B or intermediate according to the timing of peak discharge during the cardiac cycle. In contrast, there have been far fewer studies of the common small laboratory mammals such as the rat. Using several ex‐vivo rat cavo‐atrial preparations, a total of 30 successful single cavo‐atrial mechanosensory recordings were obtained. These experiments show that the rat possesses type A, B and intermediate atrial mechanoreceptors as described for larger mammals. Recording these cavo‐atrial receptors proved challenging from the main vagus but direct recording from the cardiac vagal branch greatly increased the yield of mechanically sensitive single units. In contrast to type A units, type B atrial mechanoreceptor activity was never observed at room temperature but required elevation of temperature to a more physiological range in order to be detected. The adequate stimulus for these receptors remains unclear however, type A atrial receptors appear insensitive to direct atrial stretch when applied using a programmable positioner. The findings suggest that type A and type B atrial receptors utilise different molecular transduction mechanisms.

Citation

Campbell, T., Shenton, F., Lucking, E., Pyner, S., & Jones, J. (2020). Electrophysiological characterisation of atrial volume receptors using ex‐vivo models of isolated rat cardiac atria. Experimental Physiology, 105(12), 2190-2206. https://doi.org/10.1113/ep088972

• Journal Article Type: Article
• Acceptance Date: Oct 12, 2020
• Online Publication Date: Nov 6, 2020
• Publication Date: Nov 30, 2020
• Deposit Date: Oct 15, 2020
• Publicly Available Date: Nov 6, 2021
• Journal: Experimental Physiology
• Print ISSN: 0958-0670
• Electronic ISSN: 1469-445X
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 105
• Issue: 12
• Pages: 2190-2206
• DOI: https://doi.org/10.1113/ep088972