Renal involvement in leptospirosis: the effect of glycolipoprotein on renal water absorption.
BACKGROUND
Leptospirotic renal lesions frequently produce a polyuric form of acute kidney injury with a urinary concentration defect. Our study investigated a possible effect of the glycolipoprotein, (GLPc) extracted from L. interrogans, on vasopressin (Vp) action in the guinea pig inner medullary collecting duct (IMCD).


METHODS
The osmotic water permeability (Pf µm/s) was measured by the microperfusion in vitro technique. AQP2 protein abundance was determined by Western Blot. Three groups were established for study as follows: Group I, IMCD from normal (ngp, n = 5) and from leptospirotic guinea-pigs (lgp-infected with L. interrogans serovar Copenhageni, GLPc, n = 5); Group II, IMCD from normal guinea-pigs in the presence of GLPc (GLPc group, n = 54); Group III, IMCD from injected animals with GLPc ip (n = 8).


RESULTS
In Group I, PFS were: ngp--61.8±22.1 and lgp--8.8±12.4, p<0.01 and the urinary osmolalities were: lgp--735±64 mOsm/Kg and ngp--1,632±120 mOsm/Kg. The lgp BUN was higher (176±36 mg%) than the ngp (56±9 mg%). In Group II, the Pf was measured under GLPc (250 µg/ml) applied directly to the bath solution of the microperfused normal guinea-pig IMCDs. GLPc blocked Vp (200 pg/ml, n = 5) action, did not block cAMP (10(-4) M), and Forskolin (Fors--10(-9) M) action, but partially blocked Cholera Toxin (ChT--10(-9) M) action. GLP from L.biflexa serovar patoc (GLPp, non pathogenic, 250 µg) did not alter Vp action. In Group III, GLPc (250 µg) injected intraperitoneally produced a decrease of about 20% in IMCD Aquaporin 2 expression.


CONCLUSIONS
The IMCD Pf decrease caused by GLP is evidence, at least in part, towards explaining the urinary concentrating incapacity observed in infected guinea-pigs.
Basic Research Lab-LIM 12, Nephrology-HCFMUSP, São Paulo, São Paulo, Brazil.
Katia Regina
KR
Cesar
Eliete Caló
EC
Romero
Ana Carolina
AC
de Bragança
Roberta Morozetti
RM
Blanco
Patrícia Antonia Estima
PA
Abreu
Antonio José
AJ
Magaldi
D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology; D006023:Glycoproteins / Q000302:isolation & purification / Q000494:pharmacology*; D006168:Guinea Pigs; D007685:Kidney Tubules, Collecting / Q000187:drug effects* / Q000502:physiology; D007921:Leptospira interrogans / Q000378:metabolism*; D007922:Leptospirosis / Q000382:microbiology / Q000473:pathology*; D010539:Permeability; D014882:Water-Electrolyte Balance / Q000187:drug effects* / Q000502:physiology
D051399:Aquaporin 2; D001426:Bacterial Proteins; D006023:Glycoproteins