Role of Ascorbic Acid in Cardiovascular Performance During Acute Hemorrhage

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Abstract:

Acute hemorrhage is associated with a decrease in cardiac function and contractility, increase in heart rate and fall in blood pressure. Decreased myocardial function and contractility have been shown to be caused by generation of free radicals in the ischemic myocardium. These toxic effects can be significantly attenuated by pretreatment of animals with superoxide dismutase and catalase, suggesting the involvement of free radicals in the depression of cardiovascular function. In the present study, the role of ascorbic acid as a free radical scavenger in protection from the deleterious effects of excess blood loss was examined.

The study was conducted on healthy mongrel dogs anesthetized with _-chloralose (80mg / kg, intravenous) maintained on artificial ventilation using a respiratory pump. Catheterisation was done to measure arterial blood pressure, left ventricular pressure, cardiac output, cardiac contractility, right atrial pressure and heart rate. All parameters were recorded on a polygraph. Cardiac output was measured by the thermodilution technique. Hemorrhage was induced by withdrawing 40% of estimated total blood volume in steps of 10% each at 10 min intervals. Arterial blood samples were withdrawn at each step for malondialdehyde (MDA) estimation. After inducing 40% hemorrhage, ascorbic acid was given as a bolus injection (70 mg / kg) in one group whereas, the other group received a continuous slow infusion of ascorbic acid (15 mg / min for an hour). After treatment, all the above-mentioned cardiovascular parameters were recorded and MDA estimation was done at 1, 15, 30, 45 and 60 min in both the groups.

A fall in all the cardiovascular parameters was observed on hemorrhage. MDA rose from the basal level of 2.56 ± 0.7 nmol / dl to 3.3 ± 1.0 nmol / dl (p<0.05). Immediately after treatment, MDA level fell to 0.76 ± 0.03 nmol / min. This transient rise in MDA level observed at 40% blood loss suggests involvement of free radicals in the pathogenesis of the consequences of hemorrhage. Administration of ascorbic acid resulted in the recovery of hemodynamic parameters, which were adversely influenced by the induction of hemorrhage.

Our results demonstrate the involvement of oxidants in hemorrhage-induced cardiovascular depression and cardioprotection by ascorbic acid, an antioxidant. The restoration of cardiovascular parameters towards normalcy by ascorbic acid was largely due to its antioxidant activity with a smaller contribution by the auto regulatory compensatory mechanisms.

Keywords: acute hemorrhage; ascorbic acid; cardiac contractility; free radicals

Document Type: Review Article

DOI: http://dx.doi.org/10.2174/1567270043480878

Affiliations: Department of Physiology Vallabhbhai Patel Chest Institute, University of Delhi, Delhi-110 007, India.

Publication date: March 1, 2004

More about this publication?
  • Vascular Disease Prevention publishes reviews as well as original papers to update all those concerned with this topic at the clinical or scientific level. In addition to clinically relevant topics, we consider reviews and original papers dealing with the more scientific aspects of vascular disease prevention. This includes the evaluation of emerging vascular risk factors, research dealing with the pathogenesis of atherosclerosis and the investigation of new treatment options both at the clinical and scientific level (e.g. epidemiology, patient-based studies, experimental models, in vitro experiments or molecular research). Therefore, another function of Vascular Disease Prevention is to bridge the gap between clinical practice and ongoing laboratory-based research.

    In particular, we welcome critical reviews and comments on recent trials. This is a topic that requires regular updates because of the large number of trials published every year.

    Debates are encouraged in the correspondence section of this journal.
    The editorial structure of Vascular Disease Prevention is set up with the aim of dealing with the submitted material as rapidly as possible. Specialist editors will provide a more expert and rapid assessment unlike a more centralized editorial structure.
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