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Glucocorticoid-induced alterations in the rabbit heart
Abstract:
Daily intramuscular injection of the synthetic glucocorticoid, betamethasone, into rabbits for 2 weeks resulted in both gross and microscopic alteration of cardiac muscle. A 30 per cent increase in heart weight was based on increased muscle fiber size occasioned by the deposition of fibrillo-granular material (not glycogen in nature) in the cytosol. At the same time, some myocytes underwent profound myolysis, predominantly at the nuclear poles, occasionally pervading the entire cell. Conventional lysosomes were not increased in number or size, but certain cells possessed prominent cytoplasmic vacuoles that sometimes contained mitochondria. The biochemical basis for these cardiac changes is undetermined, but the obvious ultrastructural damage produced by betamethasone, particularly dissolution of myofibrils, may prove to have clinical significance.
Insights
Betamethasone, a synthetic glucocorticoid, caused significant cardiac muscle damage in rabbits after two weeks of daily injections. This study highlights potential clinical risks associated with betamethasone use.
Area of Science:
- Cardiovascular Science
- Pharmacology
- Toxicology
Background:
- Synthetic glucocorticoids like betamethasone are widely used for their anti-inflammatory properties.
- Potential side effects of glucocorticoids on cardiac tissue require thorough investigation.
Purpose of the Study:
- To investigate the cardiac effects of daily intramuscular betamethasone injections in rabbits.
- To identify gross and microscopic alterations in cardiac muscle following betamethasone administration.
Main Methods:
- Rabbits received daily intramuscular injections of betamethasone for two weeks.
- Cardiac muscle was examined for gross changes and subjected to microscopic analysis.
Main Results:
- A 30% increase in heart weight was observed, attributed to enlarged muscle fibers.
- Fibrillo-granular material, not glycogen, was deposited in the cytosol of myocytes.
- Myolysis (muscle cell breakdown) occurred, particularly near the nucleus, and cytoplasmic vacuoles containing mitochondria were noted.
Conclusions:
- Daily betamethasone administration induces significant ultrastructural damage to cardiac muscle in rabbits.
- The observed myofibril dissolution suggests potential clinical implications for betamethasone therapy.