Hormonal regulation of renomedullary hyaluronan.
OBJECTIVE
Hyaluronan (HA) is involved in renomedullary water handling through its water-binding capacity. This study addressed the effect of hormones involved in regulating fluid-electrolyte homeostasis on renomedullary HA content in vivo and in vitro.


METHODS
The kidneys from rats treated with L-NAME, indomethacin, vasopressin (AVP) or methylprednisolone (MP) during euvolaemia or water loading were analysed for HA by RIA, ELISA and histochemical staining. HA was measured in renomedullary interstitial cells treated with AVP, angiotensin II (Ang II) or a combination of AVP and Ang II.


RESULTS
Baseline renal cortical and medullary HA content was unaffected by 2 h of intravenous treatment with L-NAME (NOS inhibitor) or indomethacin (cyclo-oxygenase inhibitor), whereas AVP reduced medullary HA by 33%. During 2 h of acute water loading, diuresis was accompanied by an increase in renomedullary HA (+45%), but cortical HA was unaffected. In both L-NAME- and indomethacin-treated animals, the water loading-induced increase in renomedullary HA was absent, indicating involvement of NO and prostaglandins. After 7 days of MP treatment, medullary HA was reduced by 40%, but the water loading-induced elevation in HA remained. In cultured renomedullary interstitial cells, AVP reduced the HA content in the supernatant by 63%, and simultaneous treatment with Ang II reduced the HA content even further (95%).


CONCLUSIONS
AVP reduces HA content, and NO and prostaglandins are needed for the increase in HA during water loading.
Rügheimer
L
L
Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden. louise.rugheimer@mcb.uu.se
Johnsson
C
C
Maric
C
C
Hansell
P
P
D000818:Animals; D050034:Antidiuretic Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology; D002478:Cells, Cultured; D006706:Homeostasis / Q000502:physiology; D006820:Hyaluronic Acid / Q000378:metabolism*; D007213:Indomethacin / Q000494:pharmacology; D007672:Kidney Cortex / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism*; D008297:Male; D008775:Methylprednisolone / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley; D014667:Vasopressins / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology
D050034:Antidiuretic Agents; D014667:Vasopressins; D006820:Hyaluronic Acid; D019331:NG-Nitroarginine Methyl Ester; D008775:Methylprednisolone; D007213:Indomethacin