Characteristics of calcium ion influx induced by human follicular fluid in individual human sperm.
The mechanism of Ca2+ influx into human spermatozoa was investigated. Human follicular fluid (hFF), which contains progesterone, stimulated an increase in the concentration of intracellular free Ca2+ ([Ca2+]i) as measured by fluorescence spectroscopy using Fura-2/AM. The technique allowed the measurement of [Ca2+]i in individual, motile spermatozoa, by improvement of the previous methods. The role of Ca2+ channels was investigated using selective blocking agents. Neither blockade of L-type channels with verapamil or lanthanum (La3+) nor blockade of N-type channels with omega-conotoxin affected the hFF-stimulated increase in [Ca2+]i. Blockade of T-type channels with either nickel (Ni2+) or amiloride significantly reduced the hFF-stimulated increase in [Ca2+]i and amiloride significantly decreased baseline [Ca2+]i. Incubation of sperm in Na(+)-free medium did not affect [Ca2+]i, indicating that Na+/Ca2+ exchange has no major role in Ca2+ influx. The results suggest that calcium influx induced by hFF occurs via T-type voltage-independent Ca2+ channels. The method described allows accurate measurement of [Ca2+]i in individual, motile human spermatozoa.
Shiomi
H
H
Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Japan.
Yamano
S
S
Shono
M
M
Aono
T
T
D000584:Amiloride / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D005260:Female; D005456:Fluorescent Dyes; D015571:Follicular Fluid / Q000502:physiology*; D016257:Fura-2; D006801:Humans; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009532:Nickel / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D005456:Fluorescent Dyes; D011374:Progesterone; D007811:Lanthanum; D000584:Amiloride; D009532:Nickel; D014700:Verapamil; D002118:Calcium; D016257:Fura-2