When the cardiac muscle prison cell is at rest, the concentration of _____________ is greater on the outside of the cell. sodium and calcium. The cardiac cell plasma membrane is most permeable to _______________________. atomic number 19. A ___________________ drug increases the force of contraction of the heart. positive inotropic. The pneumogastric nerve nerve carry a single that decrease the heart charge per unit. Research show that in the absence of neural and hormonal in uence , the sa node generate s action potentials at a frequency of about 100 meter per minute. However, the resting heart rate is about 70 pulse per minute. What would the approximate heart rate be if the tenth cranial nerve cheek were severed? about 100 beats per minute. Muscarine is a toxicant found in poisonous mushrooms. Muscarine binds to acetylcholine receptors and mimics its action. Like pilocarpine , it decreases the heart rate .