Two Americans won the Nobel Prize in chemistry on Wednesday for discoveries about how crucial substances get in and out of cells — work that could lead to improved drugs for such disorders as epilepsy and high blood pressure.

Dr. Peter Agre, 54, of the Johns Hopkins University School of Medicine in Baltimore and Dr. Roderick Mac-Kinnon, 47, of Rockefeller University in New York will share the $1.3 million prize bestowed by the Royal Swedish Academy of Sciences.

Agre (pronounced AHG-ray) and MacKinnon did pioneering work on tunnel-like “channels” that allow water molecules and electrically charged atoms called ions to pass in and out of cells.

Agre’s lab identified the first water channel in 1991. MacKinnon was honored for illuminating the structure and function of ion channels. He discovered the first detailed structure of an ion channel in 1998.

Channels are key to such crucial activities as making the heart beat, the brain function, the kidneys work and the limbs move. When channels malfunction, the result can be a long list of diseases such as cystic fibrosis, irregular heartbeat, high blood pressure, some forms of paralysis and many disorders of the kidneys and muscle.

Medicines affecting ion channels generate billions of dollars a year for the pharmaceutical industry, and ion channels remain “outstanding targets” for developing new drugs, said Raymond Frizzell, chair of the department of cell biology and physiology at the University of Pittsburgh School of Medicine.

MacKinnon’s work should allow scientists to design new drugs for such diseases as epilepsy, high blood pressure and irregular heartbeat, said Dr. David Clapham, professor of neurobiology and cardiovascular research at Harvard Medical School.

Water channels, the focus of Agre’s work, may also lead researchers to new medicines, Frizzell said.