RNO3 QTL regulates vascular structure and arterial stiffness in the spontaneously hypertensive rat

Area of Science:

• Cardiovascular Physiology
• Genetics
• Hypertension Research

Background:

• Arterial stiffness is a key risk factor for cardiovascular diseases like hypertension and stroke.
• Understanding the genetic basis of vascular stiffness is crucial for developing targeted interventions.
• Quantitative trait loci (QTLs) provide a powerful tool for dissecting the genetic architecture of complex physiological traits.

Purpose of the Study:

• To investigate the role of a known QTL on rat chromosome 3 (RNO3) in regulating blood pressure, arterial stiffness, and cardiac structure/function.
• To identify genetic factors contributing to age-related increases in arterial stiffness.
• To characterize arterial wall structural and cellular differences associated with the RNO3 QTL.

Main Methods:

• Utilized a congenic rat model (SHR.BN3) harboring the RNO3 QTL compared to parental spontaneously hypertensive rats (SHRs).
• Measured blood pressure, pulse wave velocity (PWV) for arterial stiffness, and cardiac structure/function over time.
• Employed multiphoton microscopy to analyze cellularity and collagen content in arterial adventitia and media.
• Assessed vascular smooth muscle cell (VSMC) phenotypic diversity and contractile protein expression.

Main Results:

• No significant differences in blood pressure were observed between SHR and SHR.BN3 rats.
• SHRs exhibited significantly increased arterial stiffness (PWV) with age, alongside compensatory and decompensatory cardiac changes.
• SHR.BN3 rats showed no changes in cardiac structure or function, indicating a protective effect.
• Multiphoton microscopy revealed phenotypic diversity in VSMCs but no differences in cell numbers or proliferation rates.
• The RNO3 QTL was associated with differences in collagen, PWV, left ventricular (LV) geometry and function, and VSMC contractile proteins.

Conclusions:

• The RNO3 QTL plays a significant role in modulating arterial stiffness and associated cardiovascular phenotypes, independent of blood pressure.
• This QTL influences arterial wall composition and function, impacting cardiac remodeling.
• The SHR.BN3 congenic rat model serves as a valuable platform for further genetic dissection of arterial stiffness and cardiovascular tone.