Effects of arachnotoxin on intracellular pH and calcium in human spermatozoa

• Autor(a) principal: Romero, Fernando
• Data de Publicação: 2007
• Outros Autores: Cunha, Maria Adelaide [UNIFESP], Sanchez, Raul, Ferreira, Alice Teixeira [UNIFESP], Schor, Nestor [UNIFESP], Oshiro, Maria Etsuko Miyamoto [UNIFESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: http://dx.doi.org/10.1016/j.fertnstert.2006.11.054; http://repositorio.unifesp.br/handle/11600/29755
• topic: arachnotoxin; human sperm; intracellular calcium; pH(i); NA(+)/H+ exchanger

Objective: To determine the effect of arachnotoxin (ATx), a venom extracted from the Chilean spider Latrodectus mactans, on intracellular calcium ([Ca2+](i)) and pH (pH(i)) in capacitated human spermatozoa.Design: Spermatozoa were collected from fertile adult men (n = 8). Mobile spermatozoa were collected by the swim up technique and stimulated with the crude extract of ATx and with progesterone (P).Setting: Hospital of the Federal University of São Paulo, São Paulo, Brazil.Main outcome measure(s): [Ca2+](i) was measured in fura2-AM-loaded spermatozoa, and pHi was measured in spermatozoa loaded with the pH-sensitive dye [(2',7')-bis (carboxymethyl)-(5,6)-carboxyfluorescein]-AM (BCECF).Result(s): the ATx and P induced a biphasic change in [Ca2+](i) consisting of a peak followed by a small but sustained elevation. the response to ATx was greatly reduced by pretreatment with P. the ATx caused intracellular acidification, whereas P induced alkalinization. Blockade of the NA(+)/H+ exchanger with ethylisopropylamiloride (EIPA) sharply increased ATx-induced acidification.Conclusion(S): Arachnotoxin increased [Ca2+](i) through the opening of calcium channels and release of calcium from intracellular stores. the ATx reduced pHi in human sperm, possibly by inhibiting the Na+/H+ exchanger.