Final answer:
Drugs that increase the force of myocardial contraction are called positive inotropic agents, which increase intracellular calcium levels to enhance contractions.
Step-by-step explanation:
Drugs that increase the force of myocardial contraction are called positive inotropic agents. These drugs enhance heart muscle contractions by increasing intracellular calcium levels, which propel the contractile force of the cardiac muscle. Common synthetic positive inotropes include dopamine and isoproterenol, which mimic natural substances like epinephrine. Digitalis is another example that works by enhancing calcium availability within heart cells. Thyroid hormones and glucagon can also exert positive inotropic effects. In contrast, negative inotropic agents such as beta blockers and calcium channel blockers work to decrease myocardial contractility and are beneficial in cases like high blood pressure or angina.