Age-dependent ultrastructural changes of coronary artery in spontaneously hypertensive rats

Abstract

The age-dependent differences in basic cardiovascular parameters, geometry and structure of coronary arteries between Wistar and spontaneously hypertensive rats (SHR) were evaluated. SHR of the age 3-, 9-, 17-, and 52-week and age-matched Wistar rats were used. Blood pressure (BP) was measured by the plethysmographic method. Animals were perfused with a glutaraldehyde fixative under pressure of 90 mmHg (3-week-old) and 120 mmHg (9-, 17-, 52-week-old). Coronary arteries were processed for electron microscopy. The proportions and cross sectional areas (CSA) of extracellular matrix in intima and media, endothelial and muscle cells were determined by point counting method. Cardiac hypertrophy and except of 3-week-old rats also BP increase and coronary wall hypertrophy was found in all ontogenic periods in SHR compared to Wistar rats. Arterial wall hypertrophy was evoked by increase of CSA of medial extracellular matrix and smooth muscle cells. In 52-week-old SHR, CSA of muscle cells did not differ from that in 17-week-old SHR but the CSA of intimal and medial extracellular matrix significantly increased. The CSA of endothelial cells and CSA of intimal extracellular matrix were increased only in 52-week-old SHR. The independency between BP and trophicity of individual components of the coronary wall during ontogeny of SHR was documented.

(−)‐Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats

“…This study investigates the effect of subchronic treatment with Epi in young SHR rats, at the peripubertal age, which is a critical developmental period when BP increases rapidly in SHR [39, 40]. We show that continuous Epi treatment during this period significantly prevented BP increase and reduced spontaneous locomotor hyperactivity in SHR.…”

Microstructure-based biomechanics of coronary arteries in health and disease

“…A later study of Boulesteix et al (Boulesteix et al, 2006) found that murine coronary arteries do not contain many elastin laminae as found in aorta and carotid arteries. It was reported that the volume density of SMC was 74% while that of extracellular matrix (i.e., collagen and elastin fibers, ECM) was 17% for adult murine coronary media (Cebova and Kristek, 2011). The ratio of collagen to elastin content was 3.7 in media layer of porcine RCA (Garcia and Kassab, 2009) which was slightly larger than that of intact coronary arteries (e.g., ratio of intact canine coronary arteries was reported as 3.1 by Fischer and Llaurado, 1966) likely due to the lower ratio of collagen to elastin in adventitia.…”

“…Although much efforts have been made to quantify structural change of aorta with age (Tsamis et al, 2013), quantitative data of coronary arteries is limited (Cebova and Kristek, 2011; Ozolanta et al, 1998). Ozolanta examined structural and mechanical properties of 205 human coronary arteries (Ozolanta et al, 1998).…”

“…The deformability of vessels declines, while the walls become stiffer with an elevated tangential elastic modulus (related quantitative data is listed in Table 2). A study of septal branch of the left descending coronary artery of control Wistar rat showed that inner dimeter significantly increases compared to wall thickness (57% vs. 14%) from 3 weeks to 52 weeks, while the contents of SMCs and ECM increase 9% and 19% in media, respectively (Cebova and Kristek, 2011). The study showed that aged-induced structural change is highly associated with specimens, species and longitudinal positions.…”

“… * Data taken from studies of porcine coronary arteries (H. Chen et al, 2011a; Garcia and Kassab, 2009; Huo et al, 2013; Lu et al, 2004); ** Data from study of rat coronary artery (Cebova and Kristek, 2011); *** Data from study for canine coronary artery (Fischer and Llaurado, 1966). …”