In vivo metabolic imaging of cardiac bioenergetics in transgenic mice.

Recent advances in transgenic technology have made the mouse a particularly interesting small animal in cardiovascular research. Increasingly sophisticated experimental methods and tools are needed for detailed characterization of cardiovascular physiology and biochemistry in the mice. The objective of this study was to develop a method for noninvasive evaluation of cardiac energy metabolism in the mouse. Cardiac gated (31)P magnetic resonance spectroscopy using Image Selected in Vivo Spectroscopy (ISIS) method was applied in old mice overexpressing bovine growth hormone (bGH) (n = 5) and control mice (n = 5). The localized volumes of interest were 128 and 112 microL, respectively. Phosphocreatine-to-ATP ratio was 1.5 +/- 0.13 in the bGH mice and 2.1 +/- 0.04 in the control group (P < 0.01). The study demonstrates the feasibility of application of volume-selective (31)P MRS for evaluation of cardiac energy metabolism in the mouse under maintained physiological conditions.

Bioenergetic, functional and morphological consequences of postinfarct cardiac remodeling in the rat.

Despite recent advances in the treatment, severe chronic heart failure (CHF) remains a syndrome associated with high mortality. Therefore, the search for new agents to improve both patient symptoms and survival, as well as the pursuit for detailed knowledge about pathophysiology of the failing heart, will continue to depend on relevant animal models. Large acute myocardial infarction (MI) initiates complex changes in the geometrical, structural, and biochemical architecture of both infarcted and non-infarcted regions of ventricular myocardium, which can profoundly affect left ventricular function and prognosis. In this paper we present a new model for non-invasive cardiac (31)P MRS in the rat. Volume-selective (31)P magnetic resonance spectroscopy and echocardiography were used for evaluation of myocardial energy metabolism, cardiac morphology and function in rats 3 days and 3 weeks after induction of large MI. The phosphocreatine:adenosine triphosphate (PCr:ATP) ratio was decreased in rats with MI comparing with controls both at 3 days (1.6+/-0.06 vs 2.7+/-0.04; mean+/-s.e.m. P<0.0001) and 3 weeks (1.6+/-0.07 v 2.7+/-0.02 P<0.0001) postinfarct. The results from the study demonstrate that postinfarct cardiac remodeling is a rapid process of changes not only in cardiac geometry, structure and function but also in myocardial energy metabolism after large transmural MI in the rat.

Frozen bovine semen quality and bovine cervical mucus penetration test.

Research has been carried out to test bovine cervical mucus penetration (penetration) as a means for evaluating frozen-thawed bovine semen. A commercially available cervical mucus penetration test kit (the kit) was used. A total of 158 previously frozen semen samples collected from 61 bulls were thawed in a 37 C water-bath for 2 minutes. Four ways to estimate penetration were compared using the distance traveled during 90 minutes 1) at 21 C, or 2) at 37 C, by 3) the first solitary mobile spermatozoon, or by 4) the front of the mass of the mobile spermatozoa. Penetration was measured using phase contrast microscopy and a millimeter grid. Spermatozoal quality parameters (concentration, total motility, progressive motility, acrosome integrity, total sperm integrity and cytoplasmic droplets) were measured and the correlation to penetration was calculated. The best way to assay penetration with the kit was by measuring the penetration of the first solitary mobile spermatozoon at 37 C. Semen quality variability was significant (P < 0.05) relative to penetration. Linear correlations between penetration and acrosome integrity r=0.42 as well as between penetration and total sperm integrity r=0.53 were highly significant (P < 0.001). There was significant linear multiple regression between penetration and acrosome integrity (expressed as percentage and number) and total sperm integrity (expressed as percentage and number) (r=0.62; F=23.5147; P<0.0001). There was a significant difference between the average progressive motility of samples with penetration > 20 mm and samples with penetration 20%), but it is not useful to define the fertility level of semen samples.