Document Type : Original Article

Authors

1 Department of Allied Health Sciences, Brainware University, Barasat, West Bengal, India.

2 Department of Physiology, University of Calcutta, India.

Abstract

Background: Clinically, heart failure due to cardiac ischemia or myocardial infarction is associated with different reflex responses, including bradycardia, hypotension, and the urge to urinate or defecate. Stimulation of the cardiac nociceptors of the left ventricle initiates cardiogenic reflexes, such as the mass rectal contraction, which may be responsible for defecation urge. We aimed to study the afferent and efferent pathways responsible for this cardiogenic rectal response.
 
Methods: Experiments were performed on artificially ventilated anesthetized cats of either sex. Myocardial ischemia was induced by occluding the main left anterior descending coronary artery (LAD), and rectal movement was recorded. The effects of LAD occlusion on intact and sectioned left inferior cardiac sympathetic, cardiac vagus, gastric vagus, splanchnic, inferior mesenteric ganglion, and pelvic nerves on the rectal response were studied.
 
Results: LAD occlusion induced a biphasic rectal response, which was abolished after sectioning the left inferior cardiac sympathetic nerve but not by cardiac vagotomy. The same response was also abolished by pelvic nerve sectioning. Moreover, the relaxation and contractile phase was abolished by nitric oxide and cholinergic inhibitors.
 
Conclusions: The defecatory urge associated with cardiac ischemia was due to the reflexogenic contraction of the rectal muscle. The afferent and efferent pathways for this reflex were the cardiac sympathetic nerve and the pelvic nerve, respectively. Additionally, nitric oxide and cholinergic pathways were associated with this reflex (Iranian Heart Journal 2024; 25(1): 6-18)

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