J. Venom. Anim. Toxins incl. Trop. Dis.

Vol.9, No.2, p.562, 2003.

Poster - ISSN 1678-9199.

ACUTE EFFECTS OF MICROCYSTIN-LR ON THE INTESTINAL FUNCTION IN RATS: A PRELIMINARY STUDY

Nobre,A.C.L.; Nunes-Monteiro,S.M.; Monteiro, M.C.S.A.; Havt, A.; Facó, P.E.G.; Barbosa, P.S.F.; Angelim, E.V.; Martins, A.M.C.; Lima, A.A.M.; Monteiro, H.S.A.

Department of Physiology and Pharmacology, Federal University of Ceará, Ceará, Fortaleza, Brazil

Objective: Microcystins, the cyclic heptapeptide toxins produced by freshwater cyanobacteria like Microcystis aeruginosa. The most common and potently toxic of these toxins is microcystin-LR (MCLR). The aim of the present investigation was to examine the intestinal functional effect caused by microcystin-LR.

Methodology: Adult both sexes Wistar rats weighing 180-200 g were anesthetized with ketamine (60 mg.kg^-1 body weight, IM) and xylazine (10 mg.kg^-1 body weight, IM). Animals were fasted prior experimentation for 24 hours with access to water ad libitum. The 30 cm of proximal and distal of intestine was cannulated. The solution with Ringer or MCLR (1mg/ml) was administrated by proximal cannula, using a Holter Roller Pump with reduced flow (0,16 ml/min). The perfusate was collected each 20 minutes during 100 minutes. Then, the samples were analyzed for sodium, potassium, chloride and osmolarity. Data were analyzed by unpaired Student t Test (*p<0,05).

Results: MCLR inhibited significantly the intestinal transport (mEq/min/g) of chloride (Control: 4,011±0,046 vs MCLR:-1,850±0,1848), potassium (Control:-0,418±0,039 vs MCLR:-0,225±0,011), sodium (Control:-4,637±0,565 vs MCLR:-1,360±0,064), osmolarity (Control:-8,467±0,863 vs MCLR:-0,473±0,447), but did not changed water transportation (Control: -0,006±0,0006 vs MCLR: 0,004±0,0007 mL/min/g).

Conclusions: MCLR increase the osmolarity and decrease ions transport but did not altered water transport in the isolated intestinal loop. Maybe microcystin is able to increase intestinal ions reabsorption.

Financial support: CNPq and CAPES.

CORRESPONDENCE TO:

ArlandiaCristina Lima Nobre, Rua Capitão Melo 3921 ap-202 bloco B, Fortaleza, CE, CEP: 60120-220, Brasil, Email: arlandia@zipmail.com.br