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Male Fertility: What Really Makes Sperm Swim?

by Jennifer Redmond, Feb. 15, 2010

Until now, it wasn’t really clear what makes sperm swim. It turns out that the PH of the environment they’re in is key. According to Polina Lishko, PhD, a researcher at University of California, San Francisco, and lead author of a recent study published in the February 5, issue of Cell, PH is the issue.

The PH in the male reproductive tract is low – or acidic. And, says Lishko, “low PH keeps the sperm immotile.” When exposed to a higher (or alkaline) PH, as they are in the female reproductive tract, sperm start swimming – and they release protons that increase their internal PH level. The study identifies these PH-changing protons as Hv1 channels in the sperm’s tail. When the Hv1 channel opens, according to Lishko, the protons leave the sperm, raising their internal PH. Once the sperm reach the fallopian tubes -- a more PH-friendly environment -- they really get moving.

This new research may open new doors to treating male infertility as well as preventing pregnancy.

Zinc inhibits Hv1 -- and the highest concentration of zinc in humans is found in the male reproductive tract. Not only does the female reproductive tract have a higher PH level, but it is also low in zinc. Men with zinc deficiencies are less fertile – if a man does not have enough zinc in his system the sperm cells may be prematurely activated and “burn out”.

Lishko says this new information may also open up avenues to developing a contraceptive that is not hormone-based. She cautions, however, that more research is required.

Read more about male fertility here