Passive mechanical properties of cardiac tissues in heart hypertrophy during pregnancy

• Published in: The journal of physiological sciences Vol. 59; no. 5; pp. 391 - 396
• Main Authors: Virgen-Ortiz, Adolfo, Marin, J L, Elizalde, A, Castro, E, Stefani, E, Toro, L, Muñiz, J
• Format: Journal Article
• Language: English
• Published: Japan Springer Japan 01.09.2009
• Subjects: Animals; Biomechanical Phenomena; Cardiomegaly - pathology; Cardiomegaly - physiopathology; Disease Models, Animal; Elasticity - physiology; Female; Heart - physiopathology; Myocardial Contraction - physiology; Myocardium - pathology; Myocytes, Cardiac - pathology; Organ Size - physiology; Original Paper; Pregnancy; Pregnancy Complications, Cardiovascular - pathology; Pregnancy Complications, Cardiovascular - physiopathology; Pregnancy, Animal - physiology; Rats; Rats, Sprague-Dawley
• ISSN: 1880-6546; 1880-6562
• DOI: 10.1007/s12576-009-0047-5

We evaluated changes in passive mechanical properties in cardiac tissues during rat pregnancy. Left and right ventricular free walls were dissected from hearts of nonpregnant, late-pregnant, and postpartum rats. Mechanical experiments in ventricular strips were done by stretch-release cycles using a step motor. The results show that during pregnancy, there is cardiac hypertrophy associated with (1) an increase in myocyte size, particularly of augmented myocyte length, (2) a decrease in passive tension developed by the myocardial walls, and (3) a decrease in both elastic modulus and hysteresis. All changes observed during rat pregnancy were reversed during postpartum. In conclusion, a heart with less ventricular rigidity could contribute to facilitating the ventricular filling in conditions of a greater circulating volume characteristic of pregnancy.