cyclic-gmp and Ventricular-Dysfunction

The mean age of the open-heart surgical patient is increasing every year. Therefore, it is logical to define the aging-related changes in cardiovascular function. This study set forth to define the major molecular and performance alterations that occur in the left ventricle related to advanced aging or senescence. In the human, vascular pathologies usually accompany left ventricular dysfunction. The aim of this study was to associate the altered left ventricular mechanics with molecular pathways in mice who lacked these associated vascular pathologies. This study compared the left ventricular function of two groups of mice (N = 20 each), 6 months old and 16 months old (senescent). The mice were anesthetized with urethane and alpha-chloralose, and a Millar 1.4 Fr. conductance micromanometer catheter was placed into the left ventricle for acquisition of pressure-volume loops. Heart tissues were collected immediately for analysis of cGMP concentrations. The cardiac index, preload recruitable stroke work, and the slope (Ees) of the end-systolic pressure volume relationship were significantly less in the senescent group compared to the young mice. It was concluded that the aged heart has significantly reduced systolic and diastolic dysfunction compared to the young heart function and that this dysfunction may be related to pathways leading to increased myocardial cGMP concentrations.

Topics: Age Factors; Aging; Animals; Cardiopulmonary Bypass; Cyclic GMP; Immunoenzyme Techniques; Male; Mice; Mice, Inbred C57BL; Myocardium; Ventricular Dysfunction; Ventricular Function, Left

This study examined the effects of burn injury on coronary endothelial function and coronary vascular reactivity. Adult rabbits were given a scald burn over 30% of the total body surface area (or sham burn for controls) and resuscitated with Ringer's lactate solution (4 ml/kg/% burn). Subgroups of burned (n = 6) and sham-burned (n = 6) animals were sacrificed at 2, 6, and 24 hr after injury; hearts were harvested and perfused. Changes in coronary perfusion pressure (CPP, mmHg) and coronary vascular resistance (CVR, mmHg/min) were determined at a constant preload and constant coronary flow rate. Changes in coronary endothelial function were determined by the ability of the endothelium to release cGMP as an indicator of nitric oxide production. Compared to values measured in sham burns, CPP and CVR progressively fell during the early postburn period but increased toward values measured in the sham burn group by 24 hr. Cyclic GMP, fmole/ml of coronary perfusate, was significantly lower in burned hearts (27 +/- 1) compared to values measured in effluents from sham burn hearts (310 +/- 40, P < 0.05). Alterations in coronary effluent cGMP levels after burn injury suggest that thermal injury disrupts coronary endothelial function, likely contributing to postburn changes in cardiac performance.

Topics: Acetylcholine; Animals; Burns; Coronary Vessels; Cyclic GMP; Endothelium, Vascular; In Vitro Techniques; Myocardial Contraction; Nitroprusside; Rabbits; Ventricular Dysfunction