SEQUENTIAL SECRETION OF RAT SUBMANDIBULAR KALLIKREIN AND PEROXIDASE DURING INTERMITTENT SYMPATHETIC-STIMULATION

Secretion of peroxidase from acinar cells, true tissue kallikrein (rK1 ) from granular tubules and total protein have been assessed in sequen tial samples of rat submandibular saliva formed during intermittent pe riods of sympathetic stimulation in bursts of 50 Hz 1 s every 10 a at 5 V, for 1 or 2 min each with 2 min intervals between periods. This pr otocol was repeated twice after 1 h rest pauses. The salivary flow rem ained greater throughout than when using ongoing burst stimulation, Pr otein secretion was considerable in the first 2 samples (1 min followe d by 2 min) reaching the remarkable concentration of 285 +/- 14.4 mg/m l, then it gradually decreased with little recovery after h pauses. rK 1 outputs followed a similar pattern. Peroxidase, however, showed no g reater output in initial samples and continued steadily in similar amo unts throughout. When intermittent stimulations were used for 1 sequen ce only (total stimulation time = 9 min) the glands showed 84 +/- 2.6% depletion of rK1 compared to the control glands. A correspondingly la rge depletion of granules occurred from the granular tubules on the st imulated side, which was greater than with ongoing burst stimulation f or 1 h (Garrett et al., 1991). Thus, secretion of rK1 from the granule s in granular tubules occurs most efficiently with short sharp bursts of high frequency sympathetic stimulation but soon diminishes. In cont rast, peroxidase secretion from acinar cells continues steadily and mo re modestly for long periods of time undiminished.