Dilating arteries decreases which of the following?

Dilating arteries primarily decreases afterload. Afterload refers to the resistance that the left ventricle must overcome to pump blood into the systemic circulation. When the arteries dilate, the vascular resistance in the systemic circulation decreases, allowing the heart to eject blood more easily. This reduction in afterload can improve cardiac efficiency and overall function.

The concept of preload, which is the volume of blood in the ventricles at the end of diastole, is influenced by the volume of blood returning to the heart and is not directly affected by arterial dilation. Cardiac output, a measure of the volume of blood the heart pumps per minute, can be influenced by both heart rate and stroke volume; however, it is not directly decreased by arterial dilation when afterload is lowered. Heart rate is regulated primarily by the autonomic nervous system and does not have a direct relationship with the dilation of peripheral arteries.

Therefore, the best choice that reflects the physiological consequence of arterial dilation is the decrease in afterload, as this mechanism directly affects the resistance the heart must work against during systole.