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Updated: Apr 11, 2026
Primary Culture of Adult Rat Heart Myocytes
Published on: June 16, 2009
[Age-dependent peculiarities of the rat's heart cholinergic regulation]
Abstract:
In vitro and in vivo studies were performed to investigate the effects of M1-, M2-, M3-cholinoreceptors (M-AChR) blockade on the chronotropic and inotropic cardiac function in the rats of 1, 3, 6, 8 and 20 weeks old. These age groups were selected according to the development level of the autonomic regulation of the heart. It was found that the prior blockade of all three subtypes M-AChR did not prevent inhibitory effect of carbacholin on contractility of the atria and ventricles the animals of all studied age groups. The presence of the positive chronotropic response was found after blockade of M3-cholinoreceptor in 20 weeks-old rats. The absence of cardiac chronotropic response to the blockade of M2-receptor was revealed. In 3, 6, 8 weeks-old rats the selective blockade of M-AChR does not change of the heart chronotrope. At the same time, the effect of the M1- and M2-AChR blockade on myocardial contractility was revealed.
Insights
Cholinergic receptor blockade in rats reveals age-dependent effects on heart function. M1- and M2-AChR blockade impacts myocardial contractility, while M3-AChR blockade shows age-specific chronotropic responses.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
- Developmental Biology
Context:
- The autonomic nervous system regulates heart function, with muscarinic acetylcholine receptors (mAChRs) playing a key role.
- Understanding the developmental changes in cardiac autonomic regulation is crucial for comprehending physiological responses.
Purpose:
- To investigate the age-dependent effects of blocking M1, M2, and M3 muscarinic acetylcholine receptors (M-AChRs) on rat cardiac chronotropic and inotropic function.
- To determine the specific roles of different M-AChR subtypes in modulating cardiac responses across various developmental stages.
Summary:
- In vitro and in vivo studies examined M-AChR blockade in rats aged 1, 3, 6, 8, and 20 weeks.
- Blocking all M-AChR subtypes did not abolish carbacholine's inhibitory effect on atrial and ventricular contractility across all ages.
- Positive chronotropic response was observed after M3-AChR blockade in 20-week-old rats, while M2-AChR blockade showed no chronotropic effect.
- Selective M-AChR blockade did not alter heart rate in 3-8 week old rats, but M1- and M2-AChR blockade affected myocardial contractility.
Impact:
- This study elucidates the distinct roles of M-AChR subtypes in cardiac function during postnatal development.
- Findings contribute to a deeper understanding of cholinergic signaling in the developing heart.
- Provides insights into age-related differences in cardiac autonomic regulation and receptor function.
