What question did this study set out to answer?

To determine whether neuronal nitric oxide synthase (nNOS) expression in cardiac nerve cells increases and parasympathetically regulates heart rate following acute myocardial infarction.

January 29, 2002CirculationOpen Access

Augmented Expression of Neuronal Nitric Oxide Synthase in the Atria Parasympathetically Decreases Heart Rate During Acute Myocardial Infarction in Rats

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Why the study?

Does nNOS inhibition alter heart rate in rats with acute myocardial infarction?

Population

Rats with myocardial infarction evaluated at 1, 3, 7, and 14 days post-MI and controls

Comparison

1- imidazole or 1400W vs Controls (rats without MI)

Design

Preclinical

Follow-up

14 days

Authors

YTY TakimotoHyogo Medical University TATakeshi AoyamaTokai University KTKōichi TanakaKeio University

Discussion

Member takes

Implication

May indicate nNOS blunts post-MI heart rate in rats; leaves open translation to clinical autonomic therapies.

Key Points

To determine whether neuronal nitric oxide synthase (nNOS) expression in cardiac nerve cells increases and parasympathetically regulates heart rate following acute myocardial infarction.
Evaluated atrial nNOS mRNA expression via competitive RT-PCR, protein expression via Western blotting, and enzymatic activity in rats at 1, 3, 7, and 14 days after myocardial infarction (n=7 to 22 per group) compared to controls.
Assessed heart rate dynamics following intravenous administration of the nNOS/iNOS inhibitor TRIM (50 mg/kg), the selective iNOS inhibitor 1400W (10 mg/kg SC), and co-treatments with L-arginine, atropine, or propranolol.
Atrial nNOS mRNA, protein levels, and enzymatic activity significantly increased at 1, 3, and 7 days post-myocardial infarction compared with controls, with localization in atrial nerve fibers.
TRIM administration significantly increased heart rate in infarction rats compared with controls at 1, 3, and 7 days post-infarction (P<0.01), an effect blocked by L-arginine and atropine but not by propranolol or 1400W.
A strong positive correlation was identified between atrial nNOS protein expression and heart rate elevation after TRIM infusion (r=0.837, P<0.0001).

Structured PICO

Does nNOS inhibition alter heart rate in rats with acute myocardial infarction?

Population

Rats with myocardial infarction (MI) evaluated at 1, 3, 7, and 14 days post-MI (n=7 to 22 per group) and controls

Intervention

1-(2-trifluoromethylphenyl) imidazole (TRIM) (50 mg/kg IV) or 1400W (10 mg/kg SC)

Comparator

Controls (rats without MI)

Outcome

Heart rate dynamics and neuronal NO synthase (nNOS) expression and activities in the atriasurrogate

Increased nNOS expression in the atria parasympathetically decreases heart rate via NO production during acute myocardial infarction in rats.

Cite This Study

Takimoto et al. (2002) studied this question.

synapsesocial.com/papers/6a7558fbb35e02fb15034718 https://doi.org/10.1161/hc0402.102662

Topics

Echocardiography

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Augmented Expression of Neuronal Nitric Oxide Synthase in the Atria Parasympathetically Decreases Heart Rate During Acute Myocardial Infarction in Rats

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Topics

Augmented Expression of Neuronal Nitric Oxide Synthase in the Atria Parasympathetically Decreases Heart Rate During Acute Myocardial Infarction in Rats

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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