Korean J Nephrol.  2004 Nov;23(6):848-858.

Comparison of ANG II-mediated [Ca2+i, IP3 Production and [ATP]i in Isolated Renal Proximal Convoluted Tubules of Adult SHR and WKY

Affiliations
  • 1Department of Pharmacology, Inha University, College of Medicine, Korea.
  • 2Department of Toxicology, Inha University, College of Medicine, Korea. shcha@inha.ac.kr
  • 3Kidney Disease Research Group in Inha Research Institute for Medical Sciences of Inha University, Incheon, Korea.

Abstract

BACKGROUND
The renin angiotensin syaimstem plays an important role in hypertension. Therefore, the purpose of this study was to investigate the comparison of responsiveness to angiotensin II (ANG II) in isolated renal proximal convoluted tubules of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. METHODS: Intracellualr calcium concentration ([Ca2+i) was measured using Fura- 2/AM, inositol trisphosphate (IP3) accumulation was determined by radioimmuno assay and cellular ATP content measured using the microchemilunescene method in renal proximal tubule suspension or isolated renal proximal tubules. RESULTS: When measured the ANG II-induced [Ca2+i, the young rats showed a greater response to ANG II than adult rats in both strains. The ANG II (10-7 M)-induced [Ca2+i transient in the cortical tubule suspension from adult SHR was significantly lower than that in age-matched WKY. In isolated proximal tubule segments, ANG II-induced [Ca2+i increment was only observed in S1 segments. Comparing responsiveness to ANG II in SHR and WKY, similar phenomenon was observed as experiment using tubule suspension. IP3 accumulation by ANG II also attenuated in adult SHR. The 20-minutes incubation without any exogenous substrate in proximal convoluted tubule (S1) significantly decreased cellular ATP content and ANG II (10-7 M) inhibited decrement of cellular ATP level. The effect of ANG II on cellular ATP restoration was disappeared by the treatment with losartan. CONCLUSION: From these results, the responsiveness of ANG II to AT1A receptor is attenuated in the proximal convoluted tubules of adult SHR comparing the age- mached WKY.

Keyword

Angiotensin II; Losartan; Wistar Kyoto rat (WKY); Spontaneously Hypertensive rat (SHR); Intracellular free calcium ([Ca2+i); Cellular ATP

MeSH Terms

Adenosine Triphosphate
Adult*
Angiotensin II
Angiotensins
Animals
Calcium
Humans
Hypertension
Inositol
Losartan
Rats
Renin
Adenosine Triphosphate
Angiotensin II
Angiotensins
Calcium
Inositol
Losartan
Renin
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