Abstract: TH-PO1063

Green Tea (GT) Increases Urinary Excretion of Calcium and Phosphorus, but These Effects Were Not Due to Caffeine (CAF)

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Helou, Claudia, Lab Pesquisa Basica LIM12 Fac Medicina Univ Sao Paulo, SP, Brazil, Sao Paulo, Brazil
  • Da silva, Igor Oliveira, Lab Pesquisa Basica LIM12 Fac Medicina Univ Sao Paulo, SP, Brazil, Sao Paulo, Brazil
  • Sanches, Talita R., University of Sao Paulo School of Medicine, Sao Paulo, São PAULO, Brazil
  • Santinho, Mirela, Lab Pesquisa Basica LIM12 Fac Medicina Univ Sao Paulo, SP, Brazil, Sao Paulo, Brazil
  • Andrade, Lucia, University of Sao Paulo School of Medicine, Sao Paulo, São PAULO, Brazil
Background

The consumption of industrialized (i) or natural (n) GT increases worldwide because this beverage is rich in antioxidant. However, there is a lack of studies about GT effect on the renal tubular function and a possible role exerted by the presence of CAF.

Methods

Thus, we housed Male Wistar rats in individual cages and randomly assigned them to have ad libitum access to tap water (W), iGT (Feel Good©), nGT or 8 mg% CAF dissolved in tap water. On day 8, we moved them to metabolic cages and collected 24-h urine samples. The rats were then anesthetized, and we placed a catheter in abdominal aorta to measure blood pressure (BP) and collect blood samples. We quantified creatinine and electrolytes in urine and plasma samples. We removed the kidneys to quantify protein expression (PE) of ion transporters in the cortex (C) and outer medulla (OM), by Western blot. We used ANOVA followed by Newman-Keuls test for statiscal analysis.

Results

All groups showed all ion plasma concentration values within normal range. As shown in the Table, nGT decreased BP and increased liquid intake and urine output. However, both i and n GT increased urinary excretion (UV) of calcium (Ca), phosphorus (P) and magnesium (Mg) and CAF increased only UVMg. With regard to PE of ion transporters, we only evaluated PE of TRPM6 and Na-Pi type IIa in C and PE of NKCC2 and Na-Pi type IIa in OM, and we only found decrease in PE of TRPM6 in iGT when compared with nGT, p<0.05, until now.

Conclusion

Even though we have not yet identified the mechanism for which GT induced Ca and P urinary losses we suggest to add GT in the list of risks for lithiasis.

 WiGTnGTCAF
n15131212
Body weight (b.w.),g332±9343±7337±7319±7
BP, mmHg105±2101±390±3**108±4
Creatinine clearance, ml/min/100g b.w.0.48±0.040.47±0.040.41±0.020.41±0.03
Liquid intake,ml/day24±334±345±4##36±5
Urine output,ml/day21±230±336±3##27±4
UVNa,μmol/day0.98±0.071.20±0.100.98±0.130.82±0.09
UVK,μmol/day2.4±0.12.6±0.12.5±0.22.4±0.2
UVCl,μmol/day0.71±0.080.82±0.100.44±0.070.53±0.06
UVCa,μmol/day27±242±5#39±4#34±3
UVP,μmol/day476±43686±58##655±43#529±32
UVMg,μmol/day106±14178±24##192±16##157±12#

**p<0.01 vs other groups;#p<0.05 and ##p<0.01 vs W

Funding

  • Government Support - Non-U.S.