SALIVARY SECRETION

Mechanism and control of salivary secretion

Mechanism and Control of Salivary Secretion

Introduction

To measure resting whole saliva, draining and spitting methods have been commonly used. However, these methods require the patients' understanding and cooperation. The aim of this study was to establish a method for measuring the salivary flow rate that does not rely on patient's cooperation or the state of the mouth and does not cause any discomfort to patients when performing the measurements. The salivary flow rate in the lower labial mucosal region was measured by means of strips that incorporated the iodo-starch reaction. The salivary flow rate was then calculated on the basis of the number of spots and area of discoloration on the strip. In order to test the validity of these methods, the correlation between these results and resting whole saliva measured by the draining method was also investigated. A positive correlation was found between the salivary flow rate estimated from the area of discoloration on the strip and the resting whole saliva (r=0·678, P=0·01). Therefore, these findings indicate that this is a valid method of measuring the salivary flow rate in the lower labial mucosal region.

Procedures

The laboratory activities consisted of recruiting two groups of students, Chewing-Gum and Exercise, with four students per group. All groups were first asked to collect the salivary flow from one of its members in 15-ml graded tubes for 10 min. The saliva so collected was named Control and the salivary flow in ml/min was calculated. After control measurements, the Chewing-Gum students were asked to chew a chewing gum for 10 min and simultaneously collect their saliva (Chewing-Gum Test Saliva). At the same time, the Exercise students performed an aerobic exercise (such as bicycle ergometer, jumping jack or climbing up and down the stairs) for 10 min while collecting their saliva (Exercise Test Saliva). Salivary flow was also calculated for both test groups.

Salivary amylase activity was also estimated by a simple turbidimetric analysis with a spectrophotometer. Briefly, control and test saliva were diluted 1:50 with tap water. Aliquots of 0.5 ml of each dilution were added to 5 ml of corn starch suspension (absorbance ~0.5) and immediately placed in a cuvette. The absorbance decay was monitored for 2 min (sampled each 30 s) and plotted as a function of time in a graph. Each group produced a graph showing data from control and test saliva and amylase activity compared by inclination of control and test curves.

Salivary gland secretions and morphology

Ixodid tick salivary gland secretions

Ixodid ticks are unique amongst ectoparasites in their relatively long-term association with the vertebrate host. Female lone star ticks Amblyomma americanum, for example, attach and feed slowly for 7- 14 days before a 24-48 h period of rapid feeding when they fully engorge and disengage from the host. The female increases from about 4 to 600 mg during this period of attachment. Kaufman and Phillips (1973) estimated that during the feeding cycle of Dermacentor andersoni 80% of the total meal was excreted and of this ...