An isolated gastric mucosal preparation from the dog stomach which is capable of acid secretion is described. Average values for normal resting potential difference (p.d.) was 49 +/- 2 mV (mucosal side negative with respect to the serosal side), short-circuit current (Isc) was 172 +/- 4 muA and resistance (R) was 285 +/- 6 omega.cm2. Low rates of spontaneous acid secretion (0-0.58 muequiv/cm2.hr) were present initially but following short-circuiting of the tissue these values decreased to low levels (less than 0.1 muequiv/cm2.hr) within an hour. 2. Histamine in doses exceeding 10(-6)M stimulated acid secretion, increased Isc and decreased R. Concentrations ranging from 10(-5) to 8 X 10(-4)M produced maximal secretion. The maximal secretory rate achieved was 4.24 +/- 0.35 muequiv/cm2.hr. 3. Pentagastrin (10(-8)M) and acetylcholine (10(-6)--10(-5)M) also stimulated acid secretion with a lower maximal secretion as compared to histamine stimulation. These concentrations of pentagastrin and acetylcholine did not alter histamine stimulated acid secretion. Higher concentrations of pentagastrin (10(-6)M) and acetylcholine (10(-4) M) reversibly inhibited acid secretion of histamine stimulated mucosa. 4. These results demonstrate that there are many similarities between in vitro and in vivo findings on the dog stomach, indicating the great potential of the in vitro dog gastric mucosa for studies on the mechanism of action and interaction of gastric secretagogues.
