Hormonal regulation of renomedullary hyaluronan
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 withl-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 withl-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 bothl-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%). Conclusion:
AVP reduces HA content, and NO and prostaglandins are needed for the increase in HA during water loading.
Document Type: Research Article
Affiliations: 1: Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden 2: Department of Transplantation Surgery, University Hospital, Uppsala, Sweden 3: Department of Medicine, Georgetown University Medical Centre, Washington, DC, USA
Publication date: June 1, 2008