Abstract:

Cardiac function is known to be impaired across levels of the biological organization following exposure to crude oil. Impacts on cellular function in the heart could better elucidate potential mechanisms underlying this response. Isolated mahi-mahi ventricular heart cells were exposed to either control extracellular saline, or extracellular saline containing water accommodated fraction (WAF) dilutions (10, 20, and 40%). Various aspects of contractility including sarcomere shortening, calcium handling characteristics, force frequency responses, and action potential changes were recorded using an IonOptix real-time recording system. Total polycyclic aromatic hydrocarbon (PAH) analysis was performed with gas chromatography/mass spectrometry using selective ion monitoring (GC/MS-SIM) according to the Environmental Protection Agency (EPA) method 8270D. Dilutions of high energy water accommodated fraction (HEWAF) were measured using an LS‌-45 spectrophotometer made by Perkin-Elmer.

Suggested Citation:

Heuer, R., Crossley, D.. 2019. Impacts of crude oil toxicity on mahi-mahi (Coryphaena hippurus) cardiomyocytes. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-s7d0-s364

Publications:

Heuer, R. M., Galli, G. L. J., Shiels, H. A., Fieber, L. A., Cox, G. K., Mager, E. M., … Crossley II, D. A. (2019). Impacts of Deepwater Horizon Crude Oil on Mahi-Mahi (Coryphaena hippurus) Heart Cell Function. Environmental Science & Technology, 53(16), 9895–9904. doi:10.1021/acs.est.9b03798

Purpose:

To determine the effects of crude oil on isolated heart cell function including sarcomere shortening, action potentials, and potassium handling over a range of oil concentrations.

Data Parameters and Units:

The file “Action potential and potassium currents in mahi cardiomyocytes with and without oil exposure.xlsx”; worksheet “Action potential characteristic”: contains the various responses of cells in different concentrations of oil (control, 1, 2, 5%) such as Action potential duration ninety percent (units are in milliseconds); Resting membrane potential (Vm), (units are millivolts); Action potential peak (milliVolts); Action potential rate to peak (millivolt per millisecond); Action potential time to peak (milliseconds). The worksheets “Delayed inward rectifier Ik1” and "Inward rectifier current IKr” contains information on the Current-voltage relationship for delayed inward rectifier (Ik1) and Current-voltage relationship for delayed inward rectifier (IKr) respectively at different concentrations of WAF (0 or control, 1, 2 and 5%). The headers are Peak inward rectifier circuit IKr absolute values (units are picoamperes per picofarad, pA pF-1; voltage (millivolts); Peak delayed inward rectifier (Ik1) (units are picoamperes per picofarad, pA pF-1; Cell 6 Intensity of current (picoamperes per picofarad). The file “Calcium handling characteristics of mahi cardiomyocytes.xlsx” details the effects of crude oil on calcium handling characteristics and has the following headers Voltage (millivolts); Intensity of current (picoamperes per picofarad); Interpulse duration (milliseconds); Recovery from inactivation tau (milliseconds), relative conductance (dimensionless); Half-activating potential (Vh); and Time constant of calcium current inactivation (tau). The file “Force frequency response measuring sarcomere shortening and other biophysical parameters with and without oil.xlsx”: force frequency decline (%);Departure velocity (nanometers per second); Return velocity (nanometers per second); Time at maximum departure velocity (second); Time to peak 50 percent (seconds); Time to peak 75 percent (seconds); Time to baseline 50 percent (seconds), Time to baseline 75 percent (seconds); Relaxed sarcomere length (micrometers); Relaxed sarcomere length (micrometers); and Change (delta) in sarcomere length between relaxed and contracted states(micrometers). The file “Morphometrics of mahi used in cellular experiments.xlsx” describes sizes and lengths of basic parameters and contains the headers-Animal mass (kilograms), Heart mass (grams) and Fork Length (centimeters). The file “Sarcomere shortening and other biophysical parameters of mahi cardiomyocytes with and without oil.xlsx": Percent reduction in shortening; Calculated total PAH (micrograms per liter); Absolute shortening length (micrometers), and the change (delta) between relaxed and contracted absolute shortening values for salines; Departure velocity (nanometers per second); Return velocity (nanometers per second); Time at maximum departure velocity (nanometers per second); Time at maximum return velocity (nanometers per second); Time at peak shortening (seconds); Time to peak shortening 50 percent (s); Time to baseline 50 percent (s); and Time to baseline 75 percent (s). The file “Sum PAH values for mahi cellullar experiments.xlsx”: Comparison of PAH concentration and composition before and after filtering procedures; and Composition of oil samples used for dose-response experiments. All units are in (micrograms per liter).

Methods:

Cells were obtained as outlined in previous studies (Galli et al., 2011; Shiels et al., 2004). Cells were obtained by perfusing mahi-mahi hearts with saline containing proteolytic enzymes (Trypsin and Collagenase) and bovine serum albumin. After isolation, cells were placed in fresh saline. Freshly isolated cells were diluted and stored in conical tubes near the temperature of the holding tanks of the fish. Samples for ∑PAH analysis were taken immediately after chemically enhanced water accommodated fraction (CEWAF) was made and sent to ALS Environmental (Kelso, WA) for analysis by gas chromatography/mass spectrometry with selective ion monitoring (GC/MS-SIM; based on EPA method 8270D). The dose of oil at the beginning of the experiment are given in excel file “Sum PAH values for mahi cellular experiments“.

Instruments:

Gas chromatography/mass spectrometry with selective ion monitoring. Dilutions of HEWAF were measured using an LS‌-45 spectrophotometer made by Perkin-Elmer.

Provenance and Historical References:

Galli, G. L. J., Lipnick, M. S., Shiels, H. A., & Block, B. A. (2011). Temperature effects on Ca2+ cycling in scombrid cardiomyocytes: a phylogenetic comparison. Journal of Experimental Biology, 214(7), 1068–1076. doi:10.1242/jeb.048231 Shiels, H. A., Blank, J. M., Farrell, A. P., & Block, B. A. (2004). Electrophysiological properties of the L-type Ca2+ current in cardiomyocytes from bluefin tuna and Pacific mackerel. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 286(4), R659–R668. doi:10.1152/ajpregu.00521.2003

Individual Files: