Chronotropi

Chronotropi refers to substances or stimuli that affect the heart rate. Positive chronotropic agents increase heart rate, while negative chronotropic agents decrease it. The heart rate is primarily regulated by the autonomic nervous system. The sympathetic nervous system, through the release of norepinephrine and epinephrine, has a positive chronotropic effect, speeding up the heart. Conversely, the parasympathetic nervous system, releasing acetylcholine, exerts a negative chronotropic effect, slowing down the heart. Hormones like thyroid hormone can also influence heart rate, generally exhibiting a positive chronotropic effect. Certain medications are specifically designed to be chronotropic agents, used to manage conditions like bradycardia (slow heart rate) or tachycardia (fast heart rate). For instance, beta-blockers are negative chronotropic drugs that reduce heart rate and are commonly prescribed for hypertension and heart disease. Understanding chronotropism is crucial in pharmacology and medicine for treating cardiovascular disorders and managing physiological responses to stress or exercise.