Little or no motility is observed when sperm from 5 @entity1 species are incubated in vitro in their cauda epididymal fluid (CEF). We examined the effects of pH, @entity880 , and viscoelastic drag on sperm motility to determine whether these factors are responsible for this @entity1319 . The pHs of CEF from bull, @entity235 , @entity35 , @entity840 , and hamster were 5.8, 6.2, 6.9, 6.9, and 7.2, respectively. The @entity880 concentration of epididymal semen collected from anesthetized animals ranged from 0.6 to 0.9, but increased almost 10-fold in samples from @entity35 or @entity235 when measured 2 h postmortem. Increasing the pH of CEF to 7.0 resulted in the initiation of full motility for bull and @entity235 sperm. Suspensions of sperm in buffer at various pHs (from 4.0 to 7.6) produced a sigmoidal motility curve for all species. All species, including bull and @entity235 , showed almost full motility in buffer at a pH equal to the pH of their own CEF. Motility of bull and @entity235 sperm showed greater inhibition with decreasing pH when suspended in CEF instead of buffer. The addition of 15 mM @entity880 , which has been shown to lower sperm intracellular pH, shifted the motility versus pH curves of all species toward higher pH. In bull and @entity235 the addition of @entity880 produced a motility profile that was indistinguishable from that in their own CEF. The viscoelastic drag of the CEF of only two species, @entity35 and hamster, was sufficiently high to inhibit sperm motility. We conclude that the low pH of the CEF from bulls and @entity235 plus the presence of @entity880 is sufficient to cause @entity1319 .(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pH, XXXX , and viscoelastic drag on sperm motility: a species comparison.

@entity1 :: ('9606', 'Species') :: ['mammalian'] @entity235 :: ('9615', 'Species') :: ['dog', 'dogs'] @entity840 :: ('10141', 'Species') :: ['guinea pig'] @entity880 :: ('MESH:D019344', 'Chemical') :: ['lactate'] @entity35 :: ('10116', 'Species') :: ['rat', 'rats'] @entity1319 :: ('MESH:D015835', 'Disease') :: ['inhibition of motility']
@entity880 :: (MESH:D019344,Chemical) :: ['lactate']
