Final answer:
Treatment with dobutamine, a beta-adrenergic receptor agonist, directly leads to increased stroke volume since it activates beta-1 receptors which increase both heart rate and the volume of blood pumped with each beat.
Step-by-step explanation:
The question asks about the direct consequence of treatment with dobutamine, which is an agonist of beta-adrenergic receptors on heart cells (myocytes). Dobutamine specifically targets the beta-1 adrenergic receptors. When these receptors are activated, they lead to an increase in cardiac output, which is achieved by increasing the heart rate and the volume expelled with each heartbeat (stroke volume). Therefore, the direct consequence of treatment with dobutamine would be increased stroke volume (A).
Using beta blockers as a contrasting example, these medications work by binding to the same receptors and inhibiting their action, which results in a decrease in heart rate (bradycardia) and can be used to lower blood pressure. Overprescription of beta blockers can lead to excessively low heart rates and other issues.