Which drug type has a physiological effect of increasing heart rate?

The physiological effect of increasing heart rate is primarily associated with chronotropic drugs. These types of medications directly influence the rate at which the heart beats; they can either increase or decrease the heart rate depending on their specific action. For instance, positive chronotropic agents like atropine or certain sympathomimetic drugs enhance the firing of the sinoatrial node, resulting in an elevated heart rate.

Dromotropic drugs primarily affect the conduction speed through the atrioventricular node, influencing how quickly electrical impulses travel through the heart, but they do not directly change the heart rate itself. Inotropic drugs focus on the strength of the heart's contractions, impacting cardiac output but not the heart rate. Antiarrhythmics are used to manage irregular heart rhythms; they may help stabilize rate or rhythm but are not primarily aimed at increasing heart rate. Thus, the unique action of chronotropic drugs makes them the correct answer in this context.