Evaluation of platelet function and of serum fibrinogen levels in patients bitten by snakes of the genus Crotalus: preliminary report

Submitted by Guilherme Lemeszenski ([email protected]) on 2013-08-22T19:04:08Z No. of bitstreams: 1 S0036-46651991000300009.pdf: 117928 bytes, checksum: 30abc46c537d441fad2f2fdc2716cbf7 (MD5)Made available in DSpace on 2013-08-22T19:04:08Z (GMT). No. of bitstreams: 1 S0036-46651991000300009.pdf: 117928 bytes, checksum: 30abc46c537d441fad2f2fdc2716cbf7 (MD5) Previous issue date: 1991-06-01Made available in DSpace on 2013-09-30T17:42:46Z (GMT). No. of bitstreams: 2 S0036-46651991000300009.pdf: 117928 bytes, checksum: 30abc46c537d441fad2f2fdc2716cbf7 (MD5) S0036-46651991000300009.pdf.txt: 2 bytes, checksum: e1c06d85ae7b8b032bef47e42e4c08f9 (MD5) Previous issue date: 1991-06-01Submitted by Vitor Silverio Rodrigues ([email protected]) on 2014-05-20T13:38:46Z No. of bitstreams: 2 S0036-46651991000300009.pdf: 117928 bytes, checksum: 30abc46c537d441fad2f2fdc2716cbf7 (MD5) S0036-46651991000300009.pdf.txt: 2 bytes, checksum: e1c06d85ae7b8b032bef47e42e4c08f9 (MD5)Made available in DSpace on 2014-05-20T13:38:46Z (GMT). No. of bitstreams: 2 S0036-46651991000300009.pdf: 117928 bytes, checksum: 30abc46c537d441fad2f2fdc2716cbf7 (MD5) S0036-46651991000300009.pdf.txt: 2 bytes, checksum: e1c06d85ae7b8b032bef47e42e4c08f9 (MD5) Previous issue date: 1991-06-01UNESP Hemocentro do Hospital das Clínicas Divisão de HemostasiaUNESP Faculdade de Medicina de Botucatu Depto. de UrologiaUNESP Faculdade de Medicina de BotucatuUNESP Faculdade de Medicina de Botucatu Departamento de Moléstias Infecciosas e ParasitáriasUNESP Centro de Estudos de Venenos e Animais PeçonhentosUNESP Hemocentro do Hospital das Clínicas Divisão de HemostasiaUNESP Faculdade de Medicina de Botucatu Depto. de UrologiaUNESP Faculdade de Medicina de BotucatuUNESP Faculdade de Medicina de Botucatu Departamento de Moléstias Infecciosas e ParasitáriasUNESP Centro de Estudos de Venenos e Animais Peçonhento

Crotoxin, the major toxin from the rattlesnake Crotalus durissus terrificus, inhibits ³H-choline uptake in guinea pig ileum

We examined the effect of crotoxin, the neurotoxic complex from the venom of the South American rattlesnake Crotalus durissus terrificus, on the uptake of ³H-choline in minces of smooth muscle myenteric plexus from guinea pig ileum. In the concentration range used (0.03-1 µM) and up to 10 min of treatment, crotoxin decreased ³H-choline uptake by 50-75% compared to control. This inhibition was time dependent and did not seem to be associated with the disruption of the neuronal membrane, because at least for the first 20 min of tissue exposure to the toxin (up to 1 µM) the levels of lactate dehydrogenase (LDH) released into the supernatant were similar to those of controls. Higher concentrations of crotoxin or more extensive incubation times with this toxin resulted in elevation of LDH activity detected in the assay supernatant. The inhibitory effect of crotoxin on ³H-choline uptake seems to be associated with its phospholipase activity since the equimolar substitution of Sr2+ for Ca2+ in the incubation medium or the modification of the toxin with p-bromophenacyl bromide substantially decreased this effect. Our results show that crotoxin inhibits ³H-choline uptake with high affinity (EC25 = 10 ± 5 nM). We suggest that this inhibition could explain, at least in part, the blocking effect of crotoxin on neurotransmission