Distinct hemodynamic responses to (pyr)apelin-13 in large animal models.

Area of Science:

• Cardiovascular Physiology
• Pharmacology
• Cardiac Contractility
• Coronary Blood Flow

Background:

• Pyr(apelin)-13 is a peptide with potential cardiovascular effects.
• Understanding its direct impact on myocardial contractility and coronary perfusion is crucial for therapeutic applications.
• Previous research has yielded varied results, necessitating further investigation in relevant animal models.

Purpose of the Study:

• To test the hypothesis that pyr(apelin)-13 dose-dependently augments myocardial contractility and coronary blood flow.
• To determine if these effects are independent of changes in systemic hemodynamics.
• To investigate species-specific responses in larger animal preparations (dogs and pigs).

Main Methods:

• Acute intravenous administration of pyr(apelin)-13 (10 to 1,000 nM) in anesthetized dogs and pigs.
• Measurement of systemic hemodynamics (blood pressure, heart rate) and cardiac function (left ventricular pressure/volume, dP/dt).
• Assessment of coronary blood flow and vasorelaxation in isolated coronary artery rings.

Main Results:

• In dogs, pyr(apelin)-13 increased heart rate and coronary blood flow but did not affect blood pressure or contractile indices.
• In pigs, pyr(apelin)-13 showed no significant effects on hemodynamics, coronary blood flow, or contractile function.
• Across species, cardiac output increased exponentially as peripheral resistance decreased, and a linear Frank-Starling relationship was observed.

Conclusions:

• Pyr(apelin)-13 does not directly influence myocardial contractility or coronary blood flow in dogs or pigs.
• Hemodynamic responses to pyr(apelin)-13 are species-specific and independent of direct cardiac or coronary effects.
• Findings provide critical insights into the pharmacological actions of apelin in larger animal models.