Abstract
This study examined whether substitution of chromosome 5 containing the CYP4A genes from Brown Norway rat onto the Dahl S salt-sensitive (SS) genetic background upregulates the renal production of 20-HETE and attenuates the development of hypertension. The expression of CYP4A protein and the production of 20-HETE were significantly higher in the renal cortex and outer medulla of SS.5(BN) (chromosome 5-substituted Brown Norway rat) consomic rats fed either a low-salt (LS) or high-salt (HS) diet than that seen in SS rats. The increase in the renal production of 20-HETE in SS.5(BN) rats was associated with elevated expression of CYP4A2 mRNA. MAP measured by telemetry rose from 117 ± 1 to 183 ± 5 mmHg in SS rats fed a HS diet for 21 days, but only increased to 151 ± 5 mmHg in SS.5(BN) rats. The pressure-natriuretic and diuretic responses were twofold higher in SS.5(BN) rats compared with SS rats. Protein excretion rose to 354 ± 17 mg/day in SS rats fed a HS diet for 21 days compared with 205 ± 13 mg/day in the SS.5(BN) rats, and the degree of glomerular injury was reduced. Baseline glomerular capillary pressure (Pgc) was similar in SS.5(BN) rats (43 ± 1 mmHg) and Dahl S (44 ± 2 mmHg) rats. However, Pgc increased to 59 ± 3 mmHg in SS rats fed a HS diet for 7 days, while it remained unaltered in SS.5(BN) rats (43 ± 2 mmHg). Chronic administration of an inhibitor of the synthesis of 20-HETE (HET0016, 10 mg·kg(-1)·day(-1) iv) reversed the antihypertensive phenotype seen in the SS.5(BN) rats. These findings indicate that the transfer of chromosome 5 from the BN rat onto the SS genetic background increases the renal expression of CYP4A protein and the production of 20-HETE and that 20-HETE contributes to the antihypertensive and renoprotective effects seen in the SS.5(BN) consomic strain.