ATP-sensitive inwardly rectifying potassium (KATP) channels couple cellular metabolism to the membrane potential of the cell and play an important role in a variety of tissue types, including the insect dorsal vessel, which serves as the functional equivalent of the vertebrate heart. Most of what is known about these ion channels is the result of work performed in mammalian systems, with insect studies being limited to only a few species and physiological systems. The goal of this study was to investigate the role that KATP channels play in regulating cardiac function in a model social insect, the honey bee (Apis mellifera), by examining the effect that modulators of these ion channels have on heart rate. We have developed a dissection protocol for the visualization and pharmacological modulation of bee heart rate. Using this protocol, we have demonstrated that direct application of the KATP channel antagonist tolbutamide to the exposed bee heart results in a concentration dependent decrease in heart rate, whereas the KATP channel agonist pinacidil produces a biphasic response with an increase in heart rate at low concentrations and a decrease at higher concentrations. Furthermore, known KATP channel blockers barium and magnesium also decrease heart rate in a concentration dependent manner, and we show that pretreatment with barium magnifies the effects of tolbutamide treatment and eliminates the effects of pinacidil treatment at select concentrations. The data presented here confirm a role for KATP channels in the regulation of bee dorsal vessel contractions and provide insight into the underlying physiology that governs the regulation of bee cardiac function. This work sets the stage for continuing investigation of the physiological role of KATP channels in bees.

ATP-sensitive inwardly rectifying potassium channel modulators alter cardiac function in honey bees

254th National Meeting (2017)

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