Ventricular end-diastolic volume Because most of ventricular filling occurs before atrial contraction, EDV would be minimally affected. Case 3: A high school soccer athlete with asthma is experiencing an asthma attack while at practice. This student decides to use his inhalant (a beta-receptor agonist) to treat his asthma however; he forgets the instructions from his physician and uses the inhalant twice in a short time period. Assume that the drug reached the cardiac cells through the circulation? What effect could this drug have on: Explain you answer. Beta receptors mediate the effects of epinephrine and norepinephrine in the heart Heart rate? Increase Stroke volume?