4 -, Parker KK, Taylor LK, Atkinson JB, Hansen DE, and Wikswo JP. 2001. “
The effects of tubulin-binding agents on stretch-induced ventricular arrhythmias.” European Journal of Pharmacology, 417, 1-2, Pp. 131-40.
Publisher's VersionAbstractStretch-activated ion channels have been identified as transducers of mechanoelectric coupling in the heart, where they may play a role in arrhythmogenesis. The role of the cytoskeleton in ion channel control has been a topic of recent study and the transmission of mechanical stresses to stretch-activated channels by cytoskeletal attachment has been hypothesized. We studied the arrhythmogenic effects of stretch in 16 Langendorff-perfused rabbit hearts in which we pharmacologically manipulated the microtubular network of the cardiac myocytes. Group 1 (n=5) was treated with colchicine, which depolymerizes microtubules, and Group 2 (n=6) was treated with taxol, which polymerizes microtubules. Stretch-induced arrhythmias were produced by transiently increasing the volume of a fluid-filled left ventricular balloon with a volume pump driven by a computer-controlled stepper motor. Electrical events were recorded by a contact electrode which provided high-fidelity recordings of monophasic action potentials and stretch-induced depolarizations. The probability of eliciting a stretch-induced arrhythmia increased (0.22+/-0.11 to 0.62+/-0.19, p=0.001) in hearts treated with taxol (5 microM), whereas hearts treated with colchicine (100 microM) showed no statistically significant change. We conclude that proliferation of microtubules increased the arrhythmogenic effect of transient left ventricle diastolic stretch. This result indicates a possible mode of arrhythmogenesis in chemotherapeutic patients and patients exhibiting uncompensated ventricular hypertrophy. The data would indicate that the cytoskeleton represents a possible target for antiarrhythmic therapies.
The effects of tubulin-binding agents on stretch-induced ventricular arrhythmias. 3 -, Kevin Kit Parker, James A. Lavelle, L. Katherine Taylor, Zifa Wang, and David E. and Hansen. 2001. “
Stretch-induced ventricular arrhythmias during acute ischemia and reperfusion.” Journal of Applied Physiology, 97, 1, Pp. 377-383.
Publisher's VersionAbstractMechanical stretch has been demonstrated to have electrophysiological effects on cardiac muscle, including alteration of the probability of excitation, alteration of the action potential waveform, and stretch-induced arrhythmia (SIA). We demonstrate that regional ventricular ischemia due to coronary artery occlusion increases arrhythmogenic effects of transient diastolic stretch, whereas globally ischemic hearts showed no such increase. We tested our hypothesis that, during phase Ia ischemia, regionally ischemic hearts may be more susceptible to triggered arrhythmogenesis due to transient diastolic stretch. During the first 20 min of regional ischemia, the probability of eliciting a ventricular SIA (PSIA) by transient diastolic stretch increased significantly. However, after 30 min, PSIA decreased to a value comparable with baseline measurements, as expected during phase Ib, where most ventricular arrhythmias are of reentrant mechanisms. We also suggest that mechanoelectrical coupling may contribute to the nonreentrant mechanisms underlying reperfusion-induced arrhythmia. When coronary artery occlusion was relieved after 30 min of ischemia, we observed an increase in PSIA and the maintenance of this elevated level throughout 20 min of reperfusion. We conclude that mechanoelectrical coupling may underlie triggered arrhythmogenesis during phase 1a ischemia and reperfusion.
Stretch-induced ventricular arrhythmias during acute ischemia and reperfusion. 2 -, C. Brangwynne, S Huang, K. K. Parker, D. E. Ingber, and E Ostuni. 2001. “
Symmetry breaking in cultured mammalian cells.” In Vitro Cellular & Developmental Biology - Animal, 36, 9, Pp. 563-565.
Publisher's Version Symmetry breaking in cultured mammalian cells.