Fertility and sterility · 2007
Effects of arachnotoxin on intracellular pH and calcium in human spermatozoa.
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Romero Fernando, Cunha Maria Adelaide, Sanchez Raul, Ferreira Alice Teixeira, Schor Nestor, Oshiro Maria Etsuko Miyamoto
Аннотация
OBJECTIVE: To determine the effect of arachnotoxin (ATx), a venom extracted from the Chilean spider Latrodectus mactans, on intracellular calcium ([Ca(2+)](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): [Ca(2+)](i) was measured in fura2-AM-loaded spermatozoa, and pH(i) 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 [Ca(2+)](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 [Ca(2+)](i) through the opening of calcium channels and release of calcium from intracellular stores. The ATx reduced pH(i) in human sperm, possibly by inhibiting the Na(+)/H(+) exchanger.
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): [Ca(2+)](i) was measured in fura2-AM-loaded spermatozoa, and pH(i) 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 [Ca(2+)](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 [Ca(2+)](i) through the opening of calcium channels and release of calcium from intracellular stores. The ATx reduced pH(i) in human sperm, possibly by inhibiting the Na(+)/H(+) exchanger.