CARDIAC NOCICEPTION-INDUCED URINARY-BLADDER MOVEMENT - THE AFFERENT PATHWAYS

Myocardial ischaemia stimulates ventricular nociceptors and induces va rious visceral symptoms. In cats, occlusion of the left anterior desce nding coronary artery (LAD) for 3-4 min or epicardial application of n icotine (100-200 mu g mL(-1)) for 30 s induced a biphasic change in th e urinary bladder (vesicular) motility - an initial large contraction followed by inhibition. Desensitisation of the ventricular receptors b y epicardial application of lignocaine abolished the vesicular respons es. The initial large contraction was partially prevented by bilateria l vagotomy and partially by cardiac sympathectomy. The inhibition phas e was completely abolished by cardiac sympathectomy. Spinal transectio n at the C-7-C-8 level prevented the spontaneous as well as the reflex bladder responses. Decerebration abolished the initial large contract ion and potentiated the inhibition phase. These observations indicate that ventricular receptors are involved in LAD occlusion or epicardial -nicotine induced bladder responses. Afferents for such responses run along both cardiac sympathetic and vagus, and the supraspinal centre i s involved.