Effect of acute renal decapsulation on pressure natriuresis in SHR and WKY rats

A. A. Khraibi, F. G. Knox

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Abstract

The objective of these experiments was to study pressure natriuresis in the Wistar-Kyoto (WKY) and the spontaneously hypertensive rat (SHR) during acute bilateral renal decapsulation, a maneuver that partially blocks the increase in renal interstitial hydrostatic pressure (RIHP). In control WKY rats (n = 7), at renal perfusion pressure (RPP) of 105 ± 0.7 and 125 ± 1.1 mmHg, RIHP increased from 4.4 ± 0.4 to 7.2 ± 0.7 mmHg (P < 0.05) and fractional excretion of sodium (FE(Na)) increased from 0.23 ± 0.05 to 1.32 ± 0.14% (P < 0.05). Acute bilateral renal decapsulation (n = 6) blunted the increase in RIHP observed when RPP was increased in control WKY rats and abolished the pressure natriuretic and diuretic response. When RPP was allowed to increase from 106 ± 0.8 to 130 ± 2.2 mmHg in the WKY rats with decapsulated kidneys, RIHP increased from 3.8 ± 0.5 to 4.3 ± 0.4 mmHg but FE(Na) did not significantly change (0.31 ± 0.12 to 0.43 ± 0.13%). In control SHRs (n = 7), at RPPs of 135 ± 0.8 and 163 ± 3.0 mmHg, RIHP was 4.4 ± 0.4 and 5.0 ± 0.6 mmHg (NS) and FE(Na) was 0.41 ± 0.10 and 0.82 ± 0.17% (P < 0.05). Renal decapsulation in the SHR did not affect the blunted relationships between RPP, RIHP, and FE(Na); at RPPs of 135 ± 0.3 and 162 ± 2.9 mmHg (n = 7), RIHP was 4.4 ± 0.6 and 4.7 ± 0.5 mmHg (NS) and FE(Na) was 0.43 ± 0.10 and 0.95 ± 0.22% (P < 0.05). We conclude that the renal capsule is required for the full increase in RIHP and the demonstration of the pressure natriuretic and diuretic responses in the WKY rat. In the SHR, however, the already attenuated pressure natriuretic and diuretic responses are not affected by acute bilateral renal decapsulation.

Original languageBritish English
Pages (from-to)F785-F789
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume257
Issue number5 (26/5)
DOIs
StatePublished - 1989

Keywords

  • fractional excretion of sodium
  • polyethylene matrix
  • renal capsule
  • renal interstitial hydrostatic pressure
  • renal perfusion pressure

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