Chronotropic response of spontaneously beating mouse atria to various concentrations of glucose

The effect of different concentrations of glucose on the chronotropic activity of isolated mouse atrial preparations was studied. It was found that glucose in the concentrations from 2.2 X 10(-2)M to 8.8 X 10(-2)M was ineffective to change the chronotropic activity of isolated mouse atria. Moroever, the effects of bethanechol and norepinephrine on the chronotropic activity of isolated atria were not modified in the presence of 8.8 X 10(-2)M glucose. However, it was observed that the presence of high glucose did in fact reduce the contraction amplitude, and in the presence of 8.8 X 10(-2)M, glucose, the contraction amplitude was reduced to almost 50% of its initial contraction amplitude in the bathing medium containing 1.1 X 10(-2)M glucose. Possibility to explain such phenomenon is discussed.