Newborn Organ Weight and Spontaneous Hypertension: Recombinant Inbred Strain Study

Abstract

Heart and kidney weight of newborn rats was studied in two progenitor strains (Brown Norway - BN, and spontaneously hypertensive rats - SHR) and in 31 recombinant inbred (RI) strains developed by inbreeding of F2 cross derived from these two progenitors. The relative weight of both organs was significantly higher in SHR newborns than in BN ones. No differences in relative DNA, protein and water contents were detected in hearts from SHR and BN newborns. On the other hand, in SHR kidneys there was lower DNA and protein content accompanied by a higher water content. This suggested that kidneys of SHR babies had less cells with higher water content.

The average body weight of newborns in individual RI strains was continuously distributed between both progenitor strains but more RI strains resembled values of SHR newborns. The opposite was true for relative heart and kidney weights where the predominant influence of BN genes was visible. Moreover, there was an important difference between two reciprocal crosses of RI strains because the relative heart weight was clustered around SHR values only in BxH but not in HxB cross. This was, however, not observed for body weight and relative kidney weight.

Key Words:

• newborns
• spontaneous hypertension
• blood pressure
• heart
• kidney