Correlation between haemodynamic and metabolic changes in three models of experimental cardiac hypertrophy

Area of Science:

• Cardiovascular Physiology
• Cardiac Metabolism
• Pharmacology

Background:

• Cardiac hypertrophy is a complex adaptation with varied underlying mechanisms.
• Understanding the interplay between hemodynamic changes and cellular metabolism is crucial for effective treatment strategies.

Purpose of the Study:

• To characterize three distinct models of cardiac hypertrophy (pressure overload, isoproterenol, and triiodothyronine) using hemodynamic and metabolic assessments.
• To investigate the relationship between cardiac contractility, cyclic AMP levels, and adenine nucleotide biosynthesis in these models.

Main Methods:

• Hemodynamic parameters (heart rate, left ventricular systolic pressure, maximal rate of pressure rise) were measured in closed-chest rats via left ventricular catheterization.
• Metabolic assessments included cardiac cyclic AMP levels and myocardial adenine nucleotide biosynthesis rates.
• The effect of beta-receptor blockade (propranolol) was evaluated.

Main Results:

• Aortic constriction led to decreased heart rate and increased ventricular pressure/contractility.
• Isoproterenol increased heart rate and contractility but decreased ventricular pressure.
• Triiodothyronine elevated all measured hemodynamic parameters.
• Increased contractility correlated with elevated cyclic AMP in isoproterenol and triiodothyronine models, but not pressure overload.
• Propranolol blocked adenine nucleotide biosynthesis changes in isoproterenol and triiodothyronine models, but not pressure-induced hypertrophy.

Conclusions:

• Different models of cardiac hypertrophy exhibit unique hemodynamic and metabolic profiles.
• Cyclic AMP plays a significant role in mediating contractility changes in certain hypertrophy models.
• Adenine nucleotide biosynthesis is differentially affected by beta-receptor blockade across hypertrophy models.