Blood pressure, baroreflex sensitivity, and end organ damage in hybrid offspring of spontaneously hypertensive rats and Sprague-Dawley rats

Aim: To investigate the blood pressure (BP), baroreflex sensitivity (BRS), and organ damage in hybrids of spontaneously hypertensive rats and Sprague-Dawley rats. Methods: Spontaneously hypertensive rats and Sprague-Dawley rats were crossbred, and the F-1 hybrids were inbred randomly to produce an F-2 generation. At the age of 52 weeks, the F-1 and F-2 hybrids were tested to determine BP and BRS in a conscious state. Histopathological examinations were carried out after BP recording and BRS studies. Results: BP and BRS were not different in F-1 and F-2 hybrids. BRS was inversely related to systolic BP (SBP) in male, female, or whole populations of hybrids. Quantitatively, BRS values were one-third determined by SBP level (the determinant coefficient was 0.326). The indexes for left ventricular hypertrophy, aortic hypertrophy, and renal damage were all positively related to BP, and negatively related to BRS. In multiple-regression analysis, left ventricular and aortic hypertrophy and glomerulosclerosis score were all most significantly associated with lower BRS and higher systolic BP. The contribution of BRS to left ventricular and aortic hypertrophy and glomerulosclerosis was greater than that of SBP. Conclusion: The present work with hybrid rats demonstrated quantitatively that the BRS value was one-third determined by SBP level. Both BP level and BRS value contributed greatly to the hypertensive organ damage. However, the contribution of BRS to the hypertensive organ damage was greater than that of BP level in these rats.