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Increased proteoglycan synthesis by the cardiovascular system of coarctation hypertensive rats
1Hypertension Program, University of Alabama, Birmingham 35294.
Insights
Hypertension elevates proteoglycan (PG) synthesis in rat cardiovascular tissues. Initially pressure-dependent, PG production later involves non-pressure factors, affecting all glycosaminoglycan types.
Area of Science:
- Cardiovascular Biology
- Biochemistry
- Hypertension Research
Background:
- Coarctation-induced hypertension is a model for studying cardiovascular remodeling.
- Proteoglycans (PGs) are crucial components of the cardiovascular extracellular matrix.
- Understanding PG synthesis alterations is vital for cardiovascular disease research.
Purpose of the Study:
- To investigate proteoglycan (PG) synthesis in the cardiovascular system of rats with coarctation-induced hypertension.
- To differentiate between pressure-dependent and independent mechanisms of PG production.
Main Methods:
- In vivo and in vitro labeling of glycosaminoglycans (GAGs) with 35SO4 in hypertensive rats.
- Analysis of PG synthesis rates in various cardiovascular tissues (left ventricle, aorta, right ventricle, kidney) at 4 and 14 days post-hypertension induction.
Main Results:
- In vivo labeling showed elevated PG synthesis in pressure-exposed tissues (left ventricle, aorta) after 4 days.
- By 14 days, PG synthesis increased in both pressure-exposed and protected tissues (right ventricle, kidney).
- A shift in GAG proportion was observed, with increased galactosaminoglycans and decreased heparan sulfate PGs; in vitro labeling showed no significant changes.
Conclusions:
- Coarctation hypertension initially stimulates PG production via increased pressure, with later involvement of non-pressure-related factors.
- These additional factors contribute to enhanced PG production in tissues not directly exposed to pressure overload.
- Both pressure and other factors are essential for increased PG production in this hypertension model, affecting all GAG types.
Abstract:
Proteoglycan (PG) synthesis in the cardiovascular system of coarctation hypertensive rats was examined by in vivo and in vitro labeling of glycosaminoglycans with 35SO4 in rats made hypertensive for short (4 days) and longer (14 days) durations. With in vivo labeling, only tissues directly exposed to elevated pressure (left ventricle, LV and aorta above the clip, AOR increases) exhibited elevated PG synthesis after 4 days of hypertension. By 14 days, tissues both exposed to (LV and AOR increases) and protected from elevated pressure (right ventricle and kidney) exhibited elevated PG synthetic rates. Slight elevations in the proportion of galactosaminoglycans were observed with a concurrent proportional decrease in heparan sulfate PGs. Using the in vitro labeling procedure, no significant increases in PG synthesis were observed in any tissue at either 4 days or 14 days of hypertension. These data indicate that: 1) coarctation hypertension stimulates PG production that is dependent initially on increased pressure and later, on additional non-pressure related factors, 2) these other factors are responsible for enhanced PG production in tissues not directly exposed to pressure overload, 3) pressure and/or these other factors are essential for enhanced PG production in coarctation hypertension, and 4) synthesis of all GAG types appears to be affected.