Effect of pH on endothelin-1 secretion of aortic strips.

In this study, aortic strips taken from mongrel dogs were used as experimental material. After preparation, the aortic strips were incubated in a designed control medium or an experimental medium (adding thrombin or epinephrine to the control medium). The pH value of each incubation medium mentioned above was adjusted with HCl or NaOH to a level of 8.0, 7.4, 7.0 and 6.6, respectively, in order to investigate the influence of medium acidity on the production of endothelin-1 from endothelial cells using aortic strips. After a designated time duration (one hour, three hours, six hours and 12 hours, respectively), the incubation media were collected for assay of endothelin-1. The results demonstrated that the endothelin-1 level of the incubation medium was elevated when: 1) the incubation time was lengthened; 2) the incubation medium was more acidic; 3) the aortic strips were incubated with a stimulant, such as thrombin and epinephrine; and 4) the endothelial cells on the aortic strips were intact. This indicates that the secretion of endothelin-1 is: 1) time-dependent, 2) pH-dependent, 3) stimulant-dependent and 4) endothelium-dependent.