Effect of temperature, nutrients, calcium, and cAMP on motility of human spermatozoa

The motility of human spermatozoa and its regulation were examined on cells isolated from other seminal components and purified into fractions of uniform progressive motility. The percent motile cells and estimates of their translational speed were determined by visual inspection, by stroboscopy, and by photon correlation spectroscopy; microcinematography and gradient centrifugation were occasionally used to clarify discrepancies. The motility of isolated spermatozoa could be maintained for periods up to 24 h at 4 or 37 degrees C; the presence of seminal fluid was not required and even provoked a reversible inhibition at 4 degrees C. Albumin facilitated cell movement between microscopic glass plates but had no effect on progressive motility per se, as evidenced by other techniques. During incubations of up to 2 h, progressive cell motility occurred independently of extracellular glucose and calcium but responded to variations in adenosine 3',5'-cyclic monophosphate and calcium. Dibutyryl cAMP increased forward motility, whereas ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid reversibly immobilized the spermatozoa in a calcium-dependent manner; phosphodiesterase inhibition resulted in increased vibration of sperm heads without any effect on progressive motility. Longer incubation periods required the presence of extracellular nutrients. These experiments further demonstrate that several motility measuring techniques should be used in parallel to distinguish the various components of cell movement, to exclude aspecific effects, and to supplement the shortcomings of each individual technique. Such procedure could clarify the various discrepancies that have been reported so far and should lead to a better understanding of the regulation of human sperm motility.