Meeting Abstract
The Drosophila heart is of interest as a genetic and physiologic model for developmental studies, pharmacological screening, investigating the ionic bases for pacemaker activity as well as understanding the modulation of pacemaker activity. To study cardiac physiology in vivo a suitable saline is necessary to maintain heart activity. Recently a modified HL3 saline has shown some promise in maintaining the heart rate (HR) (de Castro et al., 2014). However, this minimal saline, which is pH stable, does not maintain the HR for long periods of time for electrophysiological or imaging studies. A cocktail of OA, DA, Ach and 5-HT was shown to be beneficial to maintaining a stable heart rate for longer periods of time. Each of the modulators separately was shown to prolong and increase frequency of the HR. Even without the common hemolymph sugars trehalose and sucrose, the heart was still able to beat for long periods of time. With the cocktail of OA, DA, and 5-HT the heart rate would stay stable for about 2 hours without stopping. Recently it was demonstrated that the larval heart is sensitive to stretch and that this is likely due in part to a TRPA family of stretch activated channels. We developed an apparatus to simulate body wall contraction and relaxation on the heart tube to test the effect on maintaining the beating cycle of the heart for prolonged times. We are also examining the effect of inhibiting stretch activated ion channels in the intact larvae by RNAi knockdown.
