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Decreased monoamine oxidase activity in stroke-prone spontaneously hypertensive rat kidneys
Abstract:
The present study was undertaken to measure kidney monoamine oxidase activity (MAO) isolated from three different rat groups: Wistar Kyoto rats (WKY), stroke-free cases of stroke-prone spontaneously hypertensive rats (SHRSP-control) and SHRSP-stroke cases (SHRSP-stroke). The SHRSP group was found to have less kidney MAO than the WKY group. Conversely, plasma norepinephrine concentration of SHRSP group was significantly higher than that of the WKY group (Jpn. Heart J., 25, 833-835, 1985). These findings suggest that the increased blood pressure in SHRSP may be related to increased plasma norepinephrine concentration caused by a decrease in degradation enzyme, MAO. An attempt was also made to determine the effects of clorgyline and deprenyl. No significant difference in MAO was observed between the kidneys isolated from the WKY, SHRSP-control and SHRSP-stroke groups. However, the inhibition curve of clorgyline reached a plateau after producing 33% inhibition of MAO. It was assumed that rat kidney mitochondrial MAO consists of 33% MAO-A type and 67% MAO-B type.
Insights
Stroke-prone rats exhibit lower kidney monoamine oxidase (MAO) activity, correlating with higher norepinephrine levels and elevated blood pressure. This suggests MAO
Area of Science:
- Biochemistry
- Pharmacology
- Physiology
Background:
- Hypertension is a complex condition with multifactorial origins.
- Monoamine oxidase (MAO) enzymes play a crucial role in neurotransmitter metabolism.
- Alterations in MAO activity may contribute to the pathophysiology of hypertension.
Purpose of the Study:
- To investigate kidney monoamine oxidase (MAO) activity in different rat models.
- To explore the relationship between MAO activity, norepinephrine levels, and blood pressure.
- To characterize the types of MAO present in rat kidney mitochondria.
Main Methods:
- Kidney MAO activity was measured in Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP).
- Plasma norepinephrine concentrations were determined.
- Enzyme inhibition studies using clorgyline and deprenyl were performed to identify MAO subtypes.
Main Results:
- SHRSP rats showed significantly lower kidney MAO activity compared to WKY rats.
- Plasma norepinephrine levels were elevated in SHRSP rats.
- Clorgyline inhibition suggested rat kidney MAO comprises 33% MAO-A and 67% MAO-B.
Conclusions:
- Reduced kidney MAO activity may contribute to increased plasma norepinephrine and hypertension in SHRSP rats.
- MAO-B appears to be the predominant MAO isoform in rat kidney mitochondria.
- These findings highlight the potential role of MAO in regulating blood pressure.