Abstract
This report describes the in vivo measurement of transepithelial potential differences (PD) in rat tracheas. PD was measured both in normal tracheas (NT) and in a homografted tracheas (HGT) under various conditions. The luminal surface of both types of trachea were exposed to the following perfusion sequence: 1) HEPES (145 mM gluconate in place of NaCl); 2) HEPES (145 mM NaCl) with 100μM amiloride; 3) HEPES (145 mM glucose in place of NaCl) with 100μM amiloride; 4) HEPES (145 mM glucose in place of NaCl) with 100μM amiloride; 200μM CPT-cAMP, 10μM forscolin, 5) HEPES (145 mM NaCl). PD was significantly decreased in response to amiloride (perfusion 2), and significantly increased in Cl- free medium (perfusion 3) compared with baseline values (perfusion 1) both in NT and in HGT. No remarkable increase was observed in PD between Cl- free and Cl- free—CPT-cAMP-forsklin—containing solutions (perfusion 4). The responses seen following the addition of amiloride were indicative of sodium-absorbing respiratory eqithelia. The perfusion of Cl- free medium produced changes typical of Cl- secreting epithelium. These results suggest that HGT possesses the normal fluid transport of tracheal mucosa.
