APLN and fibrosis: This conclusion is supported by the following lines of evidence: (1) Chronic subcutaneous infusion of apelin-13 did not significantly alter blood pressure, heart rate, and cardiac morphology; (2) In contrast, chronic subcutaneous infusion of Ang II induced a dramatic elevation in blood pressure, severe cardiac hypertrophy, and fibrosis; and (3) Co-treatment with apelin-13 did not significantly alter Ang II-induced blood pressure elevation, cardiac hypertrophy, and cardiac fibrosis.