CARNAL NATION

New research helps to explain how sperm, who loaf around while in the male reproductive tract, suddenly become ambitious swimmers when they arrive inside of a woman. Though their activity level has long been associated with internal pH, new research suggests that proton release may be responsible for the change from acidic to alkaline that propels them to race to the egg.

"The concentration of protons inside the [sperm] cell is 1,000 times higher than outside," explains researcher Yuriy Kirichok. "If you just open a pore, protons will go outside. We identify the molecule that lets them out." This molecule, Hv1, operates as a pore that allows protons to leave the sperm cell.

Hv1 also is activated by endocannabinoid anandamide, which may explain why the exposure to cannabinoids, such as those contained in marijuana may impact sperm.

"Marijuana likely activates sperm prematurely, leaving them burnt out in a matter of hours," says Kirichok.

The discovery of the Hv1 channel may open doors for new methods of male contraception involving the prevention of sperm fertilization. "You can imagine now that we know the molecule responsible we could block it to prevent activation and fertilization as a kind of male contraception." Perhaps it could also be used to promote activation and fertilization with further research.