The autonomic nervous system can change the rate of the heart by: Group of answer choices beta1 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. beta2 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. muscarinic ACh receptors activation. Activation leads to reduced activity of Ca2 channels, and increasing activation of K channels, hyperpolarizing cells and reducing the rate of contraction. alpha1 adrenergic receptor activation.