Adrenergic stimulation of electrogenic K⁺ secretion in isolated mucosa from guinea pig distal colon required activation of two -adrenergic receptor sub-types (-AdrR). Addition of epinephrine (epi) or norepinephrine (norepi) to the bathing solution of mucosae in Ussing chambers increased short-circuit current (I_sc) and transepithelial conductance (G_t) consistent with this cation secretion. A -adrenergic classification was supported by propranolol antagonism of this secretory response and the lack of effect by the -AdrR antagonists BE2254 (1-AdrR) and yohimbine (2-AdrR). Sub-type selective antagonists CGP20712A (1-AdrR), ICI-118551 (2-AdrR), and SR59320A (3-AdrR) were relatively ineffective at inhibiting the epi-stimulated Isc response. In combination, CGP20712A and ICI-118551 inhibited the response which supported a synergistic action by 1-AdrR and 2-AdrR. Expression of mRNA for both 1-AdrR and 2-AdrR was indicated by RT-PCR of RNA from colonic epithelial cells. Protein expression was indicated by immuno-blot showing bands at molecular weights consistent with monomers and oligomers. Immuno-reactivity (ir) for 1-AdrR and 2-AdrR was prominent in basolateral membranes of columnar epithelial cells in the crypts of Lieberkühn as well as inter-crypt surface epithelium. Cells in the pericryptal sheath also had 1-AdrR^ir, but did not have discernable 2-AdrR^ir. The adrenergic sensitivity of K⁺ secretion measured by I_sc and G_t was relatively low as indicated by EC₅₀'s of 41±7 nM for epi and 50±14 nM for norepi. Adrenergic activation of electrogenic K⁺ secretion required the involvement of both 1-AdrR and 2-AdrR, occurring with an agonist sensitivity reduced compared to reported values for either receptor sub-type.