title: Extracellular calcium and cAMP: second messengers as "third messengers"?
abstract: Calcium and cyclic AMP are familiar second messengers that typically become elevated inside cells on activation of cell surface receptors. This article will explore emerging evidence that transport of these signaling molecules across the plasma membrane allows them to be recycled as "third messengers," extending their ability to convey information in a domain outside the cell.
authors.affiliation: Department of Surgery, VA Boston Healthcare System and Brigham & Women's Hospital, Harvard Medical School, West Roxbury, Massachusetts, USA. ahofer@rics.bwh.harvard.edu
authors.forename: Aldebaran M
authors.initials: AM
authors.lastname: Hofer
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Lefkimmiatis
mesh_terms: D000818:Animals; D019898:Autocrine Communication / Q000502:physiology; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D005110:Extracellular Space / Q000502:physiology; D006801:Humans; D019899:Paracrine Communication / Q000502:physiology*; D044169:Receptors, Calcium-Sensing / Q000502:physiology; D011953:Receptors, Cyclic AMP / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology*
chemical_list: D044169:Receptors, Calcium-Sensing; D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP; D002118:Calcium