Cell signaling. The ER doctors gave a patient an injection of epinephrine to increase his heart rate and blood pressure. The heart rate and blood pressure went up but not enough. The second dose of...

Cell signaling.

The ER doctors gave a patient an injection of epinephrine to increase his heart rate and blood pressure. The heart rate and blood pressure went up but not enough. The second dose of the same drug seemed not to have an effect. What do you think may be a possible explanation for this result?