A 57-year-old man comes to the clinic for a followup appointment. For the past two visits, his blood pressure has been 152/88 mm Hg and 150/86 mm Hg. Today, his blood pressure is 150/88 mm Hg. His past medical history is significant for an MI 2 years ago. His physician prescribes fosinopril. Which of the following parameters may change because of fosinopril therapy?