Genetic Influence on Carotid Body Structure in DBA/2J and A/J Strains of Mice

Abstract

The carotid body is a major chemosensory organ for hypoxia, hypercapnia and acidosis in the arterial blood (Fitzgerald and Shirahata 1997; Gonzalez et al., 1994). During hypoxia, the neural output from the carotid body increases and reflexly modifies several variables in the respiratory system. A prominent response is an increase in ventilation, but the hypoxic ventilatory response (HVR) among individuals varies widely (Eisele et al., 1992; Vizek et al., 1987). Studies in humans (Collins et al., 1978; Kawakami et al., 1982; Nishimura et al., 1991; Thomas et al., 1993) suggest that genetic factors significantly contribute to those differences. Similarly, studies in mice (Tankersley et al., 1994) and rats (Weil et al., 1998) clearly indicate that genetic determinants robustly influenced HVR. Among several inbred strains of mice the DBA/2J mice demonstrated the highest HVR and the A/J mice the lowest HVR (Tankersley et al., 1994). The differences in HVR between these two strains of mice may be closely related to the structural differences of the carotid body (Yamaguchi et al., 2003). The size of the carotid body and the quantity of glomus cells in the DBA/2J mice are significantly larger than those in the A/J mice. Those differences were clearly segregated between the strains, suggesting that genetic factors strongly influence the observed phenotypic differences between the DBA/2J and A/J mice. The purpose of the current study was to confirm that the morphological characteristic differences in the carotid body between the DBA/2J and A/J mice are controlled by genetic factors. Thus, we generated the first-filial progeny (F1) by a crossing the DBA/2J (female) and A/J (male) strains of mice, and examined the morphological differences of the carotid body in the DBA/2J, A/J and their F1 mice.