Renal effects and vascular reactivity induced by Tityus serrulatus venom.
Tityus serrulatus, popularly known as yellow scorpion, is one of the most studied scorpion species in South America and its venom has supplied some highly active molecules. The effects of T. serrulatus venom upon the renal physiology in human showed increased renal parameters, urea and creatinine. However, in perfused rat kidney the effects were not tested until now. Isolated kidneys from Wistar rats, weighing 240-280 g, were perfused with Krebs-Henseleit solution containing 6% (g weight) of previously dialysed bovine serum albumin. The effects of T. serrulatus venom were studied on the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), sodium tubular transport (%TNa+), potassium tubular transport (%TK+) and chloride tubular transport (%TCl-). Tityus serrulatus venom (TsV; 10 microg/mL) was added to the system 30 min after the beginning of each experiment (n=6). This 30 min period was used as an internal control. The mesenteric bed was perfused with Krebs solution kept warm at 37 degrees C by a constant flow (4 mL/min), while the variable perfusion pressure was measured by means of a pressure transducer. The direct vascular effects of TsV (10 microg/mL/min; n=6), infused at a constant rate (0.1 mL/min), were examined and compared to the infusion of the vehicle alone at the same rate. TsV increased PP (PP30'=127.8+/-0.69 vs PP60'=154.2+/-14 mmHg*, *p<0.05) and RVR (RVR30'=6.29+/-0.25 vs RVR60'=8.03+/-0.82 mmHg/mLg(-1)min(-1)*, *p<0.05), decreased GFR (GFR30'=0.58+/-0.02 vs GFR60'=0.46+/-0.01mLg(-1)min(-1)*, *p<0.05) and UF (UF30'=0.135+/-0.001 vs UF60'=0.114+/-0.003mLg(-1)min(-1)*, *p<0.05). Tubular transport was not affected during the whole experimental period (120 min). On the other hand, the infusion of TsV (10 microg/mL/min) increased the basal perfusion pressure of isolated arteriolar mesenteric bed (basal pressure: 74.17+/-3.42 vs TsV 151.8+/-17.82 mmHg*, *p<0.05). TsV affects renal haemodynamics probably by a direct vasoconstrictor action leading to decreased renal flow.
de Sousa Alves
Renata
R
Department of Physiology and Pharmacology, Institute of Biomedicine and Clinical Research Unit, Federal University of Ceara, Fortaleza, Ceara 60430-270, Brazil.
do Nascimento
Nilberto Robson Falcão
NR
Barbosa
Paulo Sérgio Ferreira
PS
Kerntopf
Marta Regina
MR
Lessa
Lucília Maria Abreu
LM
de Sousa
Clauber Mota
CM
Martins
René Duarte
RD
Sousa
Daniel Freire
DF
de Queiroz
Maria Goretti Rodrigues
MG
Toyama
Marcos Hikari
MH
Fonteles
Manassés Claudino
MC
Martins
Alice Maria Costa
AM
Monteiro
Helena Serra Azul
HS
D000818:Animals; D002712:Chlorides / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D007677:Kidney Function Tests; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology; D010477:Perfusion; D011188:Potassium / Q000378:metabolism; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology; D012604:Scorpion Venoms / Q000633:toxicity*; D013020:South America; D013997:Time Factors; D014563:Urodynamics / Q000187:drug effects / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D002712:Chlorides; D012604:Scorpion Venoms; D011188:Potassium