Abstract 13633: ZP1210, a Novel Gap Junction Modulator, Attenuates Conduction Slowing and Prevents Cx43 Dephosphorylation During Metabolic Stress
Background: ZP1210 is a novel peptide from the same family as rotigaptide (ZP123) and AAP10, which are agents known to prevent gap junctional uncoupling. We used optical mapping to assess the effects of ZP1210 on conduction and action potentials in a model of metabolic stress and used immunoblotting to assess its effects on Cx43 phophorylation in the context of regional ischaemia.
Methods: Eight Sprague-Dawley rat hearts were isolated, perfused and loaded with the voltage-sensitive dye RH237. Hearts were perfused with either 50nM ZP1210 (n=3) or control (n=5) for 20 minutes, before being subjected to metabolic stress (hypoxic hypoperfusion at 5ml/min) for 30 minutes, and a subsequent 10 minutes of reperfusion with oxygenated perfusate at normal coronary flow rates. Epicardial activation was optically mapped every minute using a 256-photodiode array. A further 7 hearts were subjected to regional left anterior descending artery ischaemia (ZP1210: n=4, control n=3) for 30 minutes. Three segments of each heart were frozen for Cx43 immunoblotting: ischaemic anterior left ventricle (ALV), non-ischaemic posterior left ventricle (PLV) and non-ischaemic right ventricle (RV).
Results: ZP1210 attenuated the conduction slowing observed after 30 mins of metabolic stress (Conduction velocity (CV) as % of baseline: ZP1210: 79.2 ± 2.7%, Control 58.9 ± 5.6% P<0.05). CV was fully restored after 10 mins reperfusion (Control: 98.1 ± 2.5%, ZP1210: 109 ± 9.3%, P=NS). Measures of optical action potential upstroke were not different between ZP1210 and control hearts after 30 mins metabolic stress (dF/dt max: ZP1210: 15.0 ± 0.4 U vs Control 16.2 ± 0.6 U; Rise time: ZP1210: 8.7 ± 0.1 ms vs Control 8.6 ± 0.2 ms; both P=NS). Optical action potential durations were also not significantly different. ZP1210 attenuated the degree of Cx43 dephosphorylation in ischaemic tissue (Phosphorylated:Total Cx43 ratio in ALV: ZP1210: 0.57 ± 0.07, Control: 0.44 ± 0.01).
Conclusions: ZP1210 attenuated the conduction slowing that occurred during metabolic stress without any changes in action potential upstroke, and likely mediated its effects by preventing gap junctional uncoupling. ZP1210 prevented acute gap junctional uncoupling by preventing metabolic stress-induced Cx43 dephosphorylation.
- © 2010 by American Heart Association, Inc.