K Saito1, A Kuroda, H Tanaka. 1. Health Service Centre, National Institute of Fitness and Sports, Kanoya, Japan.
Abstract
STUDY OBJECT: The aim was to determine whether the changes in beta adrenoceptors might be involved in the conduction system of diabetic rat hearts. DESIGN: beta Adrenoceptors in the atrioventricular node of diabetic hearts and controls were characterised by quantitative autoradiography. EXPERIMENTAL MATERIAL: The experiments were performed in five male Wistar rats injected with streptozotocin (65 mg.kg-1) to induce diabetes and in five rats injected with vehicle alone. MEASUREMENTS AND MAIN RESULTS: 125I-iodocyanopindolol binding sites decreased by 25% in atrioventricular node of diabetic hearts compared to control hearts without a significant change in the affinity. The selective beta 1 adrenoceptor antagonist CGP20712A (100 nmol.litre-1) displaced about 30% and 50% of the total atrioventricular node binding sites in diabetic and control hearts, respectively. CONCLUSIONS: These data support the concept that a decrease in beta adrenoceptors, mainly of the beta 1 subtype, in the atrioventricular node may play an important role in the cardiac conduction disturbance of diabetic animals.
STUDY OBJECT: The aim was to determine whether the changes in beta adrenoceptors might be involved in the conduction system of diabeticrat hearts. DESIGN: beta Adrenoceptors in the atrioventricular node of diabetic hearts and controls were characterised by quantitative autoradiography. EXPERIMENTAL MATERIAL: The experiments were performed in five male Wistar rats injected with streptozotocin (65 mg.kg-1) to induce diabetes and in five rats injected with vehicle alone. MEASUREMENTS AND MAIN RESULTS: 125I-iodocyanopindolol binding sites decreased by 25% in atrioventricular node of diabetic hearts compared to control hearts without a significant change in the affinity. The selective beta 1 adrenoceptor antagonist CGP20712A (100 nmol.litre-1) displaced about 30% and 50% of the total atrioventricular node binding sites in diabetic and control hearts, respectively. CONCLUSIONS: These data support the concept that a decrease in beta adrenoceptors, mainly of the beta 1 subtype, in the atrioventricular node may play an important role in the cardiac conduction disturbance of diabetic animals.
Authors: Keshore R Bidasee; Hong Zheng; Chun-Hong Shao; Sheeva K Parbhu; George J Rozanski; Kaushik P Patel Journal: J Appl Physiol (1985) Date: 2008-06-26