Measurement of cAMP in the cardiac conduction system of ratsA Sugiyama, S McKnite, P Wiegn and KG Lurie Department of Medicine, University of Minnesota, Minneapolis, USA. To characterize differences in regional cAMP production in the cardiac conduction system, 18 rats were anesthetized with pentobarbital (65 mg/kg IP) and randomized into a control (n = 9) and a stimulated group (n = 9). The stimulated group received aminophylline (20 mg/kg SC) and isoproterenol (16 micrograms/kg SC). The concentration of cAMP in freeze-dried, micro dissected pieces (1-3 micrograms) of cardiac tissue was measured using a new microanalytical method. The cAMP contents in right atrium, atrioventricular node, His bundle, and left ventricle (fmol/microgram dry weight, mean +/- SE) were 38.9 +/- 2.5, 39.0 +/- 4.3, 46.4 +/- 6.1, and 41.4 +/- 3.3 in controls and 72.9 +/- 6.7, 86.1 +/- 2.9, 115.0 +/- 11.5, and 79.5 +/- 7.3 in the stimulated group, respectively. Basal cAMP levels were similar throughout the heart, whereas isoproterenol increased cAMP levels in all regions (p < 0.01). Furthermore, cAMP levels in His bundle, after isoproterenol, were higher than in any other region (p < 0.05). These results demonstrate that: (a) cAMP can be measured in discrete portions of the cardiac conduction system; (b) there are significant regional differences of beta-adrenergic control in the cardiac conduction system; and (c) cAMP production after beta-adrenergic stimulation was lower than expected in the AV nodal region, based on previously described beta-adrenoceptor density measurements.
Volume 43,
Issue 6,
pp. 601-605,
06/01/1995
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T. A.B. van Veen, H. V.M. van Rijen, and H. J. Jongsma Electrical conductance of mouse connexin45 gap junction channels is modulated by phosphorylation Cardiovasc Res, June 1, 2000; 46(3): 496 - 510. [Abstract] [Full Text] [PDF] |
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H. V.M. van Rijen, T. A.B. van Veen, M. M.P. Hermans, and H. J. Jongsma Human connexin40 gap junction channels are modulated by cAMP Cardiovasc Res, March 1, 2000; 45(4): 941 - 951. [Abstract] [Full Text] [PDF] |
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K. G. Lurie, A. Sugiyama, S. McKnite, P. Coffeen, K. Hashimoto, and S. Motomura Modulation of AV nodal and Hisian conduction by changes in extracellular space Am J Physiol Heart Circ Physiol, March 1, 1999; 276(3): H953 - H960. [Abstract] [Full Text] [PDF] |
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