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Updated: Aug 5, 2026
Histological Quantification of Chronic Myocardial Infarct in Rats
Published on: December 11, 2016
Morphometric studies of cardiac myocytes of rats chronically treated with an organophosphate
E E Calore1, N M Perez, M M Herman
1Pathology Section, Emílio Ribas Institute, São Paulo, Brazil. eecalore@uol.com.br
Abstract:
Organophosphate intoxication induces an acute cholinergic syndrome, but the long-term effects of these compounds in the cardiocirculatory system are not known. The objective of the present work is to investigate if experimental chronic exposition to repetitive sublethal doses of organophosphate methamidophos can induce morphological changes in rat's hearts. Wistar albino adult male rats received a weekly enteral sublethal dose of the organophosphate methamidophos for 12 consecutive weeks. After that we have performed histological and morphometric studies of their hearts. We have observed hypertrophy of cardiac myocites in treated animals, which was confirmed by morphometric studies (measure of smaller diameter of cardiac myocites). One of the possible explanations for the cardiac hypertrophy would be persistent systemic arterial hypertension in treated animals. However, another possible explanation would be direct sympathetic stimulation.
Insights
Chronic exposure to organophosphate methamidophos caused cardiac myocyte hypertrophy in rats. This study investigated long-term heart effects of sublethal organophosphate doses.
Area of Science:
- Toxicology
- Cardiovascular Physiology
- Histopathology
Background:
- Organophosphate intoxication causes acute cholinergic syndrome.
- Long-term cardiocirculatory effects of organophosphates remain largely unknown.
- Investigating chronic, sublethal organophosphate exposure is crucial.
Purpose of the Study:
- To determine if chronic, sublethal methamidophos exposure induces morphological changes in rat hearts.
- To assess the long-term impact of organophosphates on cardiac structure.
- To explore potential mechanisms behind observed cardiac alterations.
Main Methods:
- Wistar albino adult male rats were administered weekly enteral sublethal doses of methamidophos for 12 weeks.
- Histological examination of cardiac tissue was performed.
- Morphometric analysis, including measurement of cardiac myocyte diameter, was conducted.
Main Results:
- Significant hypertrophy of cardiac myocytes was observed in rats exposed to methamidophos.
- Morphometric studies confirmed an increase in cardiac myocyte size (smaller diameter).
- Potential contributing factors include persistent systemic arterial hypertension or direct sympathetic stimulation.
Conclusions:
- Chronic, sublethal organophosphate exposure can lead to cardiac myocyte hypertrophy in rats.
- Methamidophos-induced cardiac changes may be linked to sustained hypertension or sympathetic nervous system activation.
- Further research is needed to elucidate the precise mechanisms of organophosphate cardiotoxicity.
