Meeting Abstract

P3-118  Monday, Jan. 6  Exposing Daphnia magna to Ethanol Results in a Decline in Heart Rate by Increasing Nitric Oxide Production CRAIG, KJ*; MERGES, C; PIRTLE, TJ; The College of Idaho; The College of Idaho; The College of Idaho kathryn.craig@yotes.collegeofidaho.edu

Daphnia magna, known as the common water flea, are small planktonic crustaceans that possess myogenic hearts – similar to those found in vertebrates. Due to this similarity, Daphnia are frequently used as model organisms to test different chemicals and their effects on the heart. In this study, we seek to understand the pharmacological effects of nitric oxide (NO) on the cardiovascular system of Daphnia. To examine changes in heart activity, Daphnia were exposed to different sets of chemicals using a perfusion system and activity was monitored using an inverted microscope. In separate experiments, Daphnia were exposed to either a NO donor, Diethylamine NONOate sodium salt hydrate or a mixture of a nitric oxide synthase (NOS) inhibitor, L-NAME hydrochloride and NO deactivator, Carboxy-PTIO, potassium salt. To determine changes in heart rate, videos were taken at regular intervals after a standard acclimatization period and stored for further analysis. We hypothesized that NO would increase Daphnia heart rate; however, Daphnia exhibited a significant decrease in heart rate when exposed to both NO and ethanol (10%) separately. Combined and simultaneous exposure of Daphnia to the NOS inhibitor (L-NAME; 100 µM) and NO deactivator (PTIO; 100 µM) in 10% ethanol mitigated the decrease in Daphnia heart rate when compared to those treated with 10% ethanol alone. Thus, our data indicates that ethanol leads to a decrease in Daphnia heart rate in part by increasing NO production.