A physiologist isolated a rat heart separated from its nerves and perfused it with an oxygenated physiological salt solution. The physiologist monitored the force of contraction and cardiac output. The physiologist decreased the volume of solution entering the heart through the atria below normal. Which of the following do you think happened next? The force of contraction and cardiac output increased. The cardiac output increased, but the force of contraction did not change. The force of contraction and cardiac output decreased. The force of contraction did not change, but the cardiac output decreased.