Effects of the beta-adrenoceptor antagonists atenolol and propranolol on human whole saliva flow rate and composition

Salivary Proteome Changes in Response to Acute Psychological Stress Due to an Oral Exam Simulation in University Students: Effect of an Olfactory Stimulus

The autonomic nervous system (ANS) plays a crucial role both in acute and chronic psychological stress eliciting changes in many local and systemic physiological and biochemical processes. Salivary secretion is also regulated by ANS. In this study, we explored salivary proteome changes produced in thirty-eight University students by a test stress, which simulated an oral exam. Students underwent a relaxation phase followed by the stress test during which an electrocardiogram was recorded. To evaluate the effect of an olfactory stimulus, half of the students were exposed to a pleasant odor diffused in the room throughout the whole session. Saliva samples were collected after the relaxation phase (T0) and the stress test (T1). State anxiety was also evaluated at T0 and T1. Salivary proteins were separated by two-dimensional electrophoresis, and patterns at different times were compared. Spots differentially expressed were trypsin digested and identified by mass spectrometry. Western blot analysis was used to validate proteomic results. Anxiety scores and heart rate changes indicated that the fake exam induced anxiety. Significant changes of α-amylase, polymeric immunoglobulin receptor (PIGR), and immunoglobulin α chain (IGHA) secretion were observed after the stress test was performed in the two conditions. Moreover, the presence of pleasant odor reduced the acute social stress affecting salivary proteome changes. Therefore, saliva proteomic analysis was a useful approach to evaluate the rapid responses associated to an acute stress test also highlighting known biomarkers.

Non-invasive monitoring of stress biomarkers in the newborn period

The neonatal period is a highly sensitive time span during which stressful experiences may have an influence on later health outcomes. Medical procedures applied to newborn babies during hospitalization are stressors that trigger a physiological and psychological stress response. Stress response has been traditionally evaluated using scores based on behavioural signs such as facial expressions, limb movements, crying, etc., which are subjectively interpreted. Only few studies have employed measurable physiological signs to objectively evaluate the stress response to specific interventions. The aim of this review is to inform of recently developed biochemical methods that allow clinicians to evaluate the stress response to medical procedures performed in the neonatal period in biological samples non-invasively obtained. Stress biomarkers are based on the physiological stress response mediated by the hypophysis-pituitary-adrenal axis and the sympathetic-adreno-medullary systems. Cortisol is at present the most widely employed laboratory determination to measure stress levels. In recent years, sequentially determined salivary cortisol levels have allowed non-invasive monitoring of newborn infants under stressful conditions in the NICU.

Salivary function impairment in type 2 Diabetes patients associated with concentration and genetic polymorphisms of chromogranin A

OBJECTIVES

The purpose of this study was to evaluate the effect of type 2 diabetes mellitus (T2DM) on salivary function impairments according to glycemic control status and subsequently compare the concentration of chromogranin A (CHGA) with its genetic profile.

MATERIALS AND METHODS

Thirty-six patients with controlled T2DM, 36 with poorly controlled T2DM, and 38 nondiabetic subjects underwent salivary flow rate measurements by means of unstimulated labial (ULS), unstimulated whole (UWS), and stimulated whole saliva (SWS) collections. CHGA concentrations were determined in saliva and plasma with ELISA, and two CHGA polymorphisms (T-415C and Glu264Asp) were analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

T2DM patients presented significantly lower ULS and UWS flow rates regardless of glycemic control status compared to controls (P = 0.002 and P = 0.027, respectively). The SWS flow rate in the poorly controlled T2DM was the lowest among the groups (P = 0.026). Significantly higher plasma and salivary CHGA levels were found in T2DM groups (P = 0.019 and P < 0.001, respectively). CHGA gene variants (T-415C and Glu264Asp) revealed significant differences between diabetics and control subjects when associated with lower salivary flow and higher salivary CHGA production (P < 0.05).

CONCLUSIONS

T2DM causes abnormalities in the function of salivary glands. However, poorly controlled T2DM has the most influence on SWS flow rates. Our findings indicate an association between plasma and salivary CHGA levels and T2DM patients. Furthermore, the results suggest that CGHA polymorphisms might be associated with salivary gland hypofunction and higher salivary CHGA production in T2DM patients. Nevertheless, further epidemiological studies are required to elucidate this clinical implication.

CLINICAL RELEVANCE

Salivary impairments and high levels of CHGA are associated with T2DM patients. In addition, CGHA polymorphisms might be associated with salivary gland hypofunction and higher salivary CHGA production in T2DM patients. This could be a significant insight to establish a role for salivary CHGA as a potential clinical biomarker to T2DM.

Salivary α-Amylase Reactivity to Laboratory Social Stress With and Without Acute Sleep Restriction

A growing literature suggests that salivary α-amylase (sAA) may serve as a minimally invasive marker of psychophysiological stress-induced activity of the sympathetic-adrenal-medullary system (SAM). Previous inconsistencies in the experimental literature relating sAA response to short sleep duration may be as a result of poor reliability of self-reported sleep time, suggesting that further examination of sAA response following verified sleep loss is required. With regard to the potential usefulness of sAA as a biomarker of psychosocial stress in the laboratory, previous research has also relied primarily on traditional psychosocial stress protocols, including physically present evaluative observers. The present study aimed to examine sAA response following a period of verified acute sleep restriction compared to a rested condition, in addition to examining the sensitivity of sAA response to a laboratory stress protocol that exposed participants to negative social evaluation presented by video relay. One hundred and eight healthy young adults (age 17–22 years; M = 18.39 years, SD = 0.87) completed a laboratory social stress task and provided saliva samples pre- and post-stressor presentation, after a night of partial sleep restriction or a full night’s rest. Marked increases in sAA activity to the video-relayed stressor were observed in both rested and sleep restricted groups. Further, sleep restricted participants exhibited significantly increased basal levels of sAA activity. The data corroborate previous limited data indicating a general upregulation of sAA activity following poor sleep and support previous findings concerning the efficacy of an experimental paradigm that presents laboratory social stress by means of video recording.

Norepinephrine infusion with and without alpha-adrenergic blockade by phentolamine increases salivary alpha amylase in healthy men

BACKGROUND

Mental stress reliably induces increases in salivary alpha amylase (sAA), a suggested surrogate marker for sympathetic nervous system (SNS) reactivity. While stress-induced sAA increases correlate with norepinephrine (NE) secretion, a potential mediating role of noradrenergic mechanisms remains unclear. In this study, we investigated for the first time in humans whether a NE-stress-reactivity mimicking NE-infusion with and without alpha-adrenergic blockade by phentolamine would induce changes in sAA.

METHODS

In a single-blind placebo-controlled within-subjects design, 21 healthy men (29-66 years) took part in three different experimental trials varying in terms of substance infusion with a 1-min first infusion followed by a 15-min second infusion: saline-infusion (trial-1), NE-infusion (5 μg/min) without alpha-adrenergic blockade (trial-2), and with phentolamine-induced non-selective blockade of alpha1- and alpha2-adrenergic receptors (trial-3). Saliva samples were collected immediately before, during, and several times after substance infusion in addition to blood pressure and heart rate readings.

RESULTS

Experimental trials significantly differed in sAA reactivity to substance-infusion (p=.001) with higher sAA reactivity following NE-infusion with (trial-3; p=.001) and without alpha-adrenergic-blockade (trial-2; p=.004) as compared to placebo-infusion (trial-1); sAA infusion reactivity did not differ between trial-2 and trial-3 (p=.29). Effective phentolamine application was verified by blood pressure and heart rate infusion reactivity. Salivary cortisol was not affected by NE, either with or without alpha-adrenergic-blockade.

CONCLUSIONS

We found that NE-infusion stimulates sAA secretion, regardless of co-administered non-selective alpha-adrenergic blockade by phentolamine, suggesting that the mechanism underlying stress-induced sAA increases may involve NE.

Diagnostic performance of initial salivary alpha-amylase activity for acute myocardial infarction in patients with acute chest pain

BACKGROUND

To rule out acute myocardial infarction (AMI) in chest pain patients constitutes a diagnostic challenge to emergency department (ED) physicians.

STUDY OBJECTIVES

To evaluate the diagnostic value of measuring salivary alpha-amylase (sAA) activity for detecting AMI in patients presenting to the ED with acute chest pain.

METHODS

sAA activity was measured in a prospective cohort of 473 consecutive adult patients within 4 h of onset of chest pain. Comparisons were made between patients with a final diagnosis of AMI and those with non-AMI. Univariate analysis and multiple logistic regression model were used to identify independent clinical predictors of AMI.

RESULTS

Initial sAA activity in the AMI group (n = 85; 266 ± 127.6 U/mL) was significantly higher than in the non-AMI group (n = 388; 130 ± 92.8 U/mL, p < 0.001). sAA activity levels were also significantly higher in patients with ST elevation AMI (n = 53) compared to in those with non-ST elevation AMI (n = 32) (300 ± 141.1 vs. 210 ± 74.1 U/mL, p < 0.001). The area under the receiver operating characteristic curve of sAA activity for predicting AMI in patients with acute chest pain was 0.826 (95% confidence interval [CI] 0.782-0.869), with diagnostic odds ratio 10.87 (95% CI 6.16-19.18). With a best cutoff value of 197.7 U/mL, the sAA activity revealed moderate sensitivity and specificity as an independent predictor of AMI (78.8% and 74.5%).

CONCLUSIONS

High initial sAA activity is an independent predictor of AMI in patients presenting to the ED with chest pain.

α-Amylase as a reliable and convenient measure of sympathetic activity: don't start salivating just yet!

Recent years have seen a growing interest in salivary α-amylase (sAA) as a non-invasive marker for sympathetic nervous system (SNS) activity. Saliva offers many advantages as a biomarker fluid and sAA is one of its most plentiful components. sAA is a digestive enzyme that breaks down starch, which provides a simple means of quantification by measuring its enzymatic activity. This commentary will address a number of common misconceptions and methodological issues that surround the use of sAA as a marker of SNS activity and limit its utility in biobehavioral research. The usefulness of sAA as an SNS marker is undermined by the fact that the parasympathetic nerves also play a significant role in sAA release. Local parasympathetic nerves regulate sAA activity via: (1) α-amylase release from glands that are solely or mainly parasympathetically innervated; (2) via synergistic sympathetic-parasympathetic effects on protein secretion (known as 'augmented secretion'); and (3) via effects on salivary flow rate. Regarding methodology, we discuss why it is problematic: (1) to ignore the contribution of salivary flow rate; (2) to use absorbent materials for saliva collection, and; (3) to stimulate saliva secretion by chewing. While these methodological problems can be addressed by using standardized and timed collection of unstimulated saliva, the physiological regulation of sAA secretion presents less resolvable issues. We conclude that at present there is insufficient support for the use and interpretation of sAA activity as a valid and reliable measure of SNS activity.

Individual differences in biological stress responses moderate the contribution of early peer victimization to subsequent depressive symptoms

RATIONALE

Some children who are exposed to early peer victimization become depressed, whereas others are resilient. Understanding individual differences in responses to early adversity, such as victimization, is critical for developing both comprehensive theoretical models and effective interventions.

OBJECTIVES

This study examined whether individual differences in biological stress responses (i.e., activation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system) moderated the contribution of peer victimization to depressive symptoms across a 1-year period.

METHODS

Children (N = 132; M age = 9.46 years, SD = 0.33) completed measures of peer victimization and depressive symptoms, and rated their ruminative responses (i.e., persistent thoughts about negative task-related emotion and experiences) to a laboratory-based social challenge task involving two conflict-of-interests situations with an unfamiliar peer. Children's saliva was collected prior to, and following, participation in the task, and was later assayed for cortisol and alpha amylase [sAA].

RESULTS

Victimization interacted with levels of cortisol measured in anticipation of the task to predict task-related rumination and depressive symptoms 1 year later, adjusting for initial symptoms. Specifically, victimization served as a risk factor for rumination and depressive symptoms in children with heightened but not dampened anticipatory cortisol; yet, heightened anticipatory cortisol was protective against rumination and depressive symptoms in low-victimized children. Victimization also predicted subsequent depressive symptoms in girls with high sAA reactivity across the task.

CONCLUSIONS

This study advances contemporary theory and research by implicating individual variation in biological stress responses as one determinant of sensitivity to the mental health effects of early adversity.

Frontiers in the use of biomarkers of health in research on stress and aging

Assessment of biomarkers that reflect objective indicators of physiological processes has become increasingly popular in psychological research on stress and aging. The current article reviews biomarkers of the neuroendocrine and immune systems, including issues related to measurement and normative age-related changes. We also discuss how exposure to stressors can provoke changes in these biomarkers and propose that stressful experiences may accelerate age-related declines in these systems. We recommend that future research examining physical health and aging incorporate dynamic and multivariate methods for assessing links between stressors and biomarkers.

Caffeine and stress alter salivary alpha-amylase activity in young men

OBJECTIVE

We examined the effects of caffeine and a psychological stressor on salivary alpha-amylase (sAA) in healthy young males (age 18-30 years) who consumed caffeine on a daily basis.

METHODS

Using a between-subjects, double-blind, placebo-controlled design, 45 participants received either 200 or 400 mg of caffeine (Vivarin) or placebo, rested for 20 min, and then performed 20 min of mental arithmetic. Saliva samples (assayed for sAA and caffeine), blood pressure, and heart rate were taken before (baseline) and 15 min after the math stressor (stress).

RESULTS

Baseline sAA activity did not differ among the treatment groups; however, there was a statistically significant time by caffeine group interaction. Changes in sAA activity across the session were dependent on the amount of caffeine consumed. Following the challenge period, sAA activity among the placebo group was the lowest and sAA activity among the 400 mg treatment group was the highest. Separate repeated-measures ANOVAs conducted for each drug treatment group revealed that sAA activity increased in response to stress and caffeine (i.e., 200 and 400 mg groups) but not to stress alone (i.e., placebo group).

CONCLUSIONS

Findings provide evidence for acute sAA changes in response to caffeine and stress in habitual caffeine users.

Medication effects on salivary cortisol: tactics and strategy to minimize impact in behavioral and developmental science

The non-invasive measurement of cortisol in saliva has enabled behavioral scientists to explore the correlates and concomitants of the interaction between the activity of the hypothalamic-pituitary-adrenal (HPA) axis, intrinsic factors, and social forces as they occur naturally in everyday life. The widespread integration of salivary cortisol into behavioral science has also revealed that omnipresent features of everyday life such as, over-the-counter and prescription medications, have the capacity to influence measurement validity. We identify several pathways by which pharmacologic agents could influence salivary cortisol, including (a) direct agonistic and antagonistic effects on the HPA axis, (b) indirect effects on physiological systems networked with the HPA axis, (c) moderation or mediation effects on cortisol secretion via pharmacologically induced change in subjective experience, (d) iatrogenic effects on the availability or composition of saliva, or the diffusion of serum constituents into oral fluid, and (e) cross-reactivities with antibodies used to detect cortisol by immunoassay. Specific medications with the capacity to influence salivary cortisol via these pathways are documented in an effort to procedurally and statistically minimize this potential source of error variance in the next generation of studies.

Endogenous noradrenergic activation and memory for emotional material in men and women

A plethora of evidence from the animal and human literature suggests that emotionally arousing material is often remembered better than is neutral material, and that this effect critically involves noradrenergic activation during and soon after exposure to the emotional material. A crucial prediction of this hypothesis is that endogenous adrenergic activation should relate positively and selectively to memory for emotional events in humans. Salivary alpha-amylase (sAA), a biomarker for adrenergic activity was measured in response to viewing a series of mixed emotional and neutral images to test this prediction in healthy men and women. One week after viewing these images subjects returned for a surprise free recall test. Endogenous noradrenergic activation, defined as an increase in sAA immediately after versus before slide viewing, occurred in 24 of 67 subjects. Regression analysis of the data revealed a significant positive correlation between the increase in sAA and the percentage of emotional pictures recalled. No correlation existed in the same subjects between sAA and the percentage of neutral pictures recalled. Additionally, the difference between these two correlations closely approached significance. The findings therefore demonstrate a relationship between a measure of endogenous noradrenergic activation and long-term memory performance in humans. The results support the view that adrenergic activation underlies enhanced memory for emotional material in humans, namely, that endogenous adrenergic activation in response to an emotional event should predict long-term memory for the event. The selectivity of the relationship for emotional, and not neutral, material supports the view derived from earlier research that stress activation does not necessarily enhance memory for all aspects of an emotional event; rather, that it acts disproportionately to influence memory for the more emotional aspects of an event. These findings are the first involving human subjects to indicate that the degree of endogenous noradrenergic activation in response to emotionally arousing stimuli predicts the strength of long-term memory for those stimuli.

Total protein of whole saliva as a biomarker of anaerobic threshold

Saliva provides a convenient and noninvasive matrix for assessing specific physiological parameters, including some biomarkers of exercise. We investigated whether the total protein concentration of whole saliva (TPWS) would reflect the anaerobic threshold during an incremental exercise test. After a warm-up period, 13 nonsmoking men performed a maximum incremental exercise on a cycle ergometer. Blood and stimulated saliva were collected during the test. The TPWS anaerobic threshold (PAT) was determined using the Dmax method. The PAT was correlated with the blood lactate anaerobic threshold (AT; r = .93, p < .05). No significant difference (p = .16) was observed between PAT and AT. Thus, TPWS provides a convenient and noninvasive matrix for determining the anaerobic threshold during incremental exercise tests.

Effect of age on flow-rate, protein and electrolyte composition of stimulated whole saliva in healthy, non-smoking women

As relatively little is known about the effect of age on salivary electrolytes we studied the composition of saliva as function of age to provide reference values for healthy non-smoking women. All non-medicated and non-smoking 30-59-year-old subjects (n=255) selected from among 1030 women participating in a screening program formed the material of the present study. Salivary calcium, inorganic phosphate, magnesium, sodium, potassium, protein and flow-rate of stimulated whole saliva were measured. We found age-related changes in salivary calcium and phosphate concentrations (p=0.001 and p=0.004, respectively, one-way ANOVA). Peak values occurred at around 50-54 years of age. Age had no effect on flow-rate, magnesium, sodium, potassium or proteins. The concentration of sodium correlated positively, while phosphate, potassium, magnesium and protein correlated negatively with the salivary flow-rate. Calcium was the only electrolyte which had no association with flow-rate. Our study provides reference values for salivary electrolytes of 30-59-year-old women.

Salivary -Amylase in Biobehavioral Research: Recent Developments and Applications

In the history of science, technical advances often precede periods of rapid accumulation of knowledge. Within the past three decades, discoveries that enabled the noninvasive measurement of the psychobiology of stress (in saliva) have added new dimensions to the study of health and human development. This widespread enthusiasm has led to somewhat of a renaissance in behavioral science. At the cutting edge, the focus is on testing innovative theoretical models of individual differences in behavior as a function of multilevel biosocial processes in the context of everyday life. Several new studies have generated renewed interest in salivary alpha-amylase (sAA) as a surrogate marker of the autonomic/sympathetic nervous system component of the psychobiology of stress. This article reviews sAA's properties and functions; presents illustrative findings relating sAA to stress and the physiology of stress, behavior, cognitive function, and health; and provides practical information regarding specimen collection and assay. The overarching intent is to accelerate the learning curve such that investigators avoid potential pitfalls associated with integrating this unique salivary analyte into the next generation of biobehavioral research.

Influence of the time of measurement of unstimulated human whole saliva on the diagnosis of hyposalivation

OBJECTIVE

An unstimulated whole saliva flow rate (UWSFR) of less than 0.1 mL/min is often related to symptoms of dry mouth. It is also used as a diagnostic criterion for Sjogren's syndrome, and for assessment of hyposalivation as a caries risk factor. The main hypothesis was that the circadian rhythm of salivary flow affects this diagnosis if saliva is collected at different morning time-points.

DESIGN

UWSFR was tested at 7:30 and 11:30 a.m. in 108 individuals, age 15-46 years (mean 33+/-9). The participants were allocated to one of three groups (very low< or =0. 1/min, low 0.1-0.2 mL/min and normal>0.2 mL/min) based on the UWSFR at 7:30 a.m. Different aspects of the perception of oral dryness were rated using Visual Analog Scales.

RESULTS

All three groups displayed a statistically significant increase in UWSFR at 11:30 a.m. compared with 7:30 a.m., all of similar magnitude (0.08-0.09 mL/min). In the group with very low UWSFR, 70% at 11:30 a.m. exceeded the 0.1 mL/min limit. There were significant difference in perception of oral dryness between the normal group and both the low and the very low groups. Only the subjects in the groups with a low or very low UWSFR perceived an increase in oral wetness at 11:30 a.m.

CONCLUSIONS

It was concluded that the time of measurement strongly influences the diagnosis of hyposalivation. To control the influence of variations in the time of saliva collection, we suggest that unstimulated whole saliva tests are performed at a fixed time-point or in a limited time interval early in the morning.

An association between oral lichen planus and a persistently dry mouth

OBJECTIVES

The aim of this study was to investigate the relationship between oral lichen planus and dry mouth by comparing xerostomia scores of individuals with oral lichen planus to those of healthy matched controls.

STUDY DESIGN

Patients who had attended 1 of 2 centers for the management of oral lichen planus (n=116), along with age- and sex-matched control subjects (n=348), were sent a questionnaire. Nonresponders were invited to complete the questionnaire by telephone in lieu of mailing a reply. A standardized medical history was obtained for all subjects.

RESULTS

The difference between patients with oral lichen planus and control subjects for all xerostomia questions was statistically significant. In the lichen planus group, the mean xerostomia score was 20.4, whereas for control patients, the mean score was 14.7 (P <.001). Stepwise conditional logistic regression analysis for the matched case-control groups was performed.

CONCLUSION

The results demonstrate an association between oral lichen planus and xerostomia in some individuals.

Xerostomia and hyposalivation

Dry mouth must not be considered a trivial problem in the population, since it constitutes a phenomenon with many aspects relative to oral function as well as quality of life. Up until today, no global consensus has been reached with regard to the terminology of dry mouth, creating a substantial problem for research, education, diagnosis, and therapy. In this report, salivary gland hypofunction has been selected as the overarching term for subjective symptoms and objective signs of dry mouth. Its different aspects--xerostomia, hyposalivation, and altered saliva composition--are reviewed with respect to prevalence, diagnosis, and etiology. It is concluded that these aspects of salivary gland hypofunction are separate entities, which in many respects are interrelated, constituting not merely a dental but also a medical and social concern.

Hyposalivation and iron stores among individuals with and without active dental caries

The aims of the study were to investigate frequencies of low unstimulated whole saliva (UWS) levels and low serum ferritin (S-f) levels among individuals with active dental caries (ADC) and dental caries inactive (DCI) individuals and to compare the relationship between UWS and S-f levels. In this descriptive study, 48 ADC patients and 48 DCI individuals were compared. The two groups were matched regarding age and sex (30 females and 18 males in each group, age range 15-40 years). In the ADC group, 32 individuals (67%) had low (< or = 0.20 ml/min) UWS levels compared with 13 individuals (27%) in the DCI group. This difference was statistically significant (P < 0.001). The mean values of UWS were significantly lower in the ADC group compared to the DCI group (mean ml/min +/- SD) 0.20 +/- 0.13 and 0.33 +/- 0.24, respectively (P = 0.002). There were significant differences for females but not for males when comparing frequencies of low UWS levels (P < 0.001) and mean UWS levels (P = 0.002). There was no difference in S-f levels between the two groups. Neither was any correlation between UWS and S-f found. In conclusion, the significant negative relationship found between UWS and ADC indicates that a suppressed defense for dental caries activity could play a more important role in ADC than previously presumed, especially among females. The absence of a correlation between UWS and S-f might indicate that saliva secretion will not be stimulated by iron supplementation.

The buffer capacity and buffer systems of human whole saliva measured without loss of CO2

The buffer capacity of unstimulated (UWS) and stimulated (SWS) whole-mouth saliva involves three major buffer systems. The aim was to determine the buffer capacity of UWS and SWS at specific pH in the interval from pH 7.5 down to pH 3.0. The contribution of each of the buffer systems was also determined under conditions resembling those in the mouth. UWS and SWS were collected from 20 healthy volunteers; the saliva was collected under paraffin oil in order to avoid loss of CO2. The buffer capacity of UWS and SWS in samples with and without bicarbonate (HCO3-) and CO2 were measured at various pH by acid titration in a closed system at 36 C. The mean concentrations of the buffer systems in UWS (mean flow rate 0.55 ml/min) were 4.4 mmol/l HCO3-, 4.5 mmol/l phosphate (of which 1.3 mmol/l was present in the form of HPO4(2-)), 1876 microg/ml protein; the saliva pH was 6.8 and the P(CO2) 29.3 mmHg. The corresponding mean concentrations in SWS (mean flow rate 1.66 ml/min) were 9.7 mmol/l HCO3-, 3.8 mmol/l phosphate (of which 1.9 mmol/l was present in the form of HPO4(2-)), 1955 microg/ml protein; pH 7.2 and P(CO2) 25.7 mmHg, The highest buffer capacity of UWS and SWS was 6.0 and 8.5 mmol H+ /(1 saliva*pH unit) at pH 6.25, respectively. At saliva pH in the range from pH 7 down to pH 5, the following had significant impact on buffer capacity: the HCO3- concentration (p < 0.001), the flow rate (p < 0.01), and the pH of the saliva (p < 0.05). At acidic pH in the range from pH 5 down to pH 4, however, only the protein concentration had a significant impact on buffer capacity (p < 0.01).

Salivary carbonic anhydrase isoenzyme VI

The carbonic anhydrases (CAs) participate in the maintenance of pH homeostasis in various tissues and biological fluids of the human body by catalysing the reversible reaction CO2 + H2O HCO3- + H+ (Davenport & Fisher, 1938; Davenport, 1939; Maren, 1967). Carbonic anhydrase isoenzyme VI (CA VI) is the only secretory isoenzyme of the mammalian CA gene family. It is exclusively expressed in the serous acinar cells of the parotid and submandibular glands, from where it is secreted into the saliva. In this review, we will discuss recent advances in research focused on the physiological role of salivary CA VI in the oral cavity and upper alimentary canal.

Xerostomia and hyposalivation: causes, consequences and treatment in the elderly

Xerostomia and salivary gland hypofunction (SGH) are prevalent in elderly populations, causing much discomfort and even difficulties in eating. SGH also increases the occurrence and severity of oral diseases and makes the patient susceptible to candidiasis. The principal causes of SGH and xerostomia are systemic diseases and drugs used daily. The diagnosis of SGH and xerostomia is based on simple methods, of which measuring both unstimulated and stimulated salivary flow rate is the most important. Treatment calls for proper management of underlying disease, avoidance of all unnecessary medications, and topical remedies such as artificial saliva substitutes. However, good hydration is essential in the elderly with SGH and xerostomia, and water is the drink of choice. In extremely difficult cases, for instance in patients receiving radiotherapy for cancer of the head and neck regions, parasympathomimetic drugs may be administered if no contraindications exist.

Effects on salivary flow rate and composition of withdrawal of and re-exposure to the beta 1-selective antagonist metoprolol in a hypertensive patient population

Secretion rates and composition of unstimulated and chewing-stimulated whole saliva and 3% citric acid stimulated parotid and submandibular-sublingual secretions were studied in 12 hypertensive patients during withdrawal of and re-exposure to antihypertensive pharmacotherapy. All the patients' blood pressures were well controlled by monotherapy with metoprolol, a beta 1-selective adrenoceptor antagonist. Blood pressure measurements and saliva sampling were performed at about 9:30 a.m., 2 h after intake of breakfast, on days 0 (medicated baseline), 7, 14, 28 (nonmedicated experimental values and nonmedicated baseline) and 35 (medicated experimental values). A significant increase in unstimulated whole saliva secretion rate was observed when metoprolol was withdrawn and a corresponding decrease when the drug was reintroduced. A positive correlation was found between diastolic blood pressure levels and chewing-stimulated whole saliva secretion rates. In unstimulated whole saliva and 3% citric acid stimulated submandibular-sublingual secretion, the output of total protein, amylase, potassium, calcium and phosphate was significantly increased during the withdrawal period and decreased when metoprolol was reintroduced. For chewing-stimulated whole saliva, the corresponding changes were restricted to output of total protein and amylase, while for citric acid stimulated parotid secretion, no changes in salivary composition were observed. Finally, in all secretions one or both of the ratios hexosamine/total protein and sialic acid/total protein were affected, indicating a possible effect of beta-adrenoceptor antagonists on salivary protein synthesis.

Effect of selected beta-blockers on supragingival calculus formation

Supragingival plaque and calculus indices, salivary flow rates, pH, ionic and total calcium concentrations, total phosphate concentration, and the number of cervical restorations and caries lesions were measured in 29 subjects using systemic beta-(beta) blockers and in 28 subjects who were not taking any systemic medication. After 8 weeks of normal oral hygiene following an oral prophylaxis, a second comparison of each of the above quantities was made. With the exception of the calculus indices and the incidence of cervical restorations, no significant differences were found for any of the measured quantities between the medicated and non-medicated groups at either examination. The medicated group showed significantly lower mean calculus values than the non-medicated group at both examinations and a higher incidence of cervical restorations at the baseline examination, suggesting that beta-blockers decrease the rate of mineralization in the oral cavity. Since beta-blockers did not appear to alter stimulated salivary pH, flow rate, phosphate, ionic calcium or total calcium concentrations, their effect on the mineralization processes must be attributed to other mechanisms. Two hypotheses appear plausible: changes in salivary mineralization rates caused by either direct physico-chemical effects of the secreted beta-blockers in the saliva, or by alterations in the salivary protein/glycoprotein composition, enzymes and oral bacterial flora owing to systemic pharmacological effects of beta-blockers.

Effects of the antihypertensive drug captopril on human salivary secretion rate and composition

The effects of the antihypertensive drug captopril on salivary secretion rate and composition was evaluated in 24 healthy adults (18-46 yr) according to a double-blind, cross-over design. Unstimulated and paraffin-chewing stimulated whole saliva and 3% citric acid stimulated parotid and submandibular-sublingual (SM-SL) secretion were collected at 10.30 a.m. (about 2h after intake of breakfast) on day 0 (baseline values), day 1 (experimental acute values) and day 7 (experimental chronic values) in each treatment period. In 8 of the subjects, also morning samples were collected at 7.30 a.m., with the test subjects in a fasting condition. Whole saliva was assessed for flow rate and for concentrations of sodium, potassium, chloride, calcium and phosphate. In addition, parotid and SM-SL secretion were assessed for concentrations of total protein, hexosamine, sialic acid, lactoferrin and salivary IgA and for activities of amylase, lysozyme and salivary peroxidase. During treatment with the angiotensin converting enzyme inhibitor captopril, the secretion rates tended to increase for unstimulated and paraffin-chewing stimulated whole saliva and for parotid secretion. For salivary composition, no alterations were observed in any of the collected secretions.

Circadian periodicity in salivary carbonic anhydrase VI concentration

Carbonic anhydrase VI (CA VI) is secreted into the saliva by the serous acinar cells of the parotid and submandibular glands. Saliva samples from six healthy male volunteers were analysed for concentrations of CA VI throughout the 24 h period by means of a specific time-resolved immunofluorometric assay and the levels were compared with amylase activity. The sleeping period was from 00.10 h to 07.30 h and the subjects had breakfast at 07.30 h and regular meals at 13.30 h and 19.30 h. Saliva secretion decreased markedly during the sleeping period in all the subjects except one. The levels of both CA VI and amylase activity varied greatly among the subjects, but in a parallel manner, and declined to a very low level during the sleeping period. Dexamethasone intake at midnight had no effect on the morning rise in either enzyme. When the sleeping period was postponed from 06.10 h to 11.30 h both enzyme concentrations declined during the night and continued to be low until the subjects awoke at 11.30 h, whereas salivary secretion was low only during the sleeping period. Our results suggest that CA VI secretion follows a circadian periodicity that is comparable to amylase secretion but independent of salivary secretion.

Physiological regulation of the secretion of histatins and statherins in human parotid saliva

The small salivary phosphoproteins, histatins and statherins, have important functions in the oral cavity in terms of antimicrobial actions and regulation of calcium phosphate homeostasis. Neither the effects of various physiological stimuli on their secretion nor the nature of the efferent receptor involved in the stimulus-secretion coupling has been determined previously. These aspects are important for improved understanding of the secretory control of salivary proteins and may have implications regarding the effects of specific medications on salivary constituents and oral health. The effects of graded mechanical (chewing on short and long silicone tubings) and gustatory stimulation (0.5, 1.5, and 5.0% citric acid) on the secretion of histatins and statherins were studied in the presence and absence of adrenolytic agents (n = 10). In this model, secretory rates of both proteins increased with increases in flow rate, with 5.0% citric acid representing a particularly potent stimulus. Histatin and statherin secretory rates were significantly reduced by the beta 1-adrenolytic agent (histatins to 58 to 72% and statherins to 11 to 29% of that in corresponding control experiments), but not by the alpha 1-adrenolytic agent. Since the beta 1-adrenergic receptors played an important role in the stimulus-secretion coupling of these proteins, protective salivary functions in the oral cavity may be compromised during beta 1-adrenolytic treatment.

Effects of the beta-adrenoceptor antagonists atenolol and propranolol on human unstimulated whole saliva flow rate and protein composition

The effects of 1-wk medication with two beta-adrenoceptor antagonists on unstimulated whole saliva flow rate and protein composition were evaluated in 11 healthy young men in a randomized, double-blind, placebo-controlled, cross-over study. Unstimulated whole saliva was collected before each treatment period and then again after 7 days. The saliva was assessed for flow rate, total protein, and hexosamine and sialic acid concentrations and for amylase activity. No significant effect on saliva secretion rate was found. A statistically significant reduction of salivary total proteins was registered during atenolol medication. The amylase activity decreased significantly during treatment with both atenolol and propranolol. Significant changes of the calculated ratios of sialic acid/hexosamine and hexosamine/total protein indicated an alteration in glandular protein synthesis after atenolol treatment.

The relationship between salivary growth factors, electrolytes and abnormal sodium transport in human hypertension

We have previously shown cheek cell Na+/H+ antiporter activity to be reduced in human hypertensives. We have now examined the relationship between abnormal antiporter activity and a variety of salivary factors. Total protein concentration and amylase activity were higher in hypertensives, but salivary flow rate and epidermal growth factor, transforming growth factor-alpha, calcium, and magnesium concentrations were not significantly different between hypertensives and normotensives. The lowered cheek cell Na+/H+ antiporter activity in those hypertensives with diastolic BP greater than 95 mmHg was accompanied by lowered salivary Na+/H+ ratios. In borderline hypertensives (diastolic BP between 90 and 95 mmHg), the Na+/H+ ratio was reduced to a similar extent to that seen in those hypertensives with a diastolic BP above 95 mmHg, however the cheek cell antiporter activity was not reduced, suggesting that these two differences are not related in a simple fashion in all hypertensives. It is concluded that it is unlikely that differences in salivary growth factors explain the lowered cheek cell Na+/H+ antiporter activity observed in human hypertension. Our findings indicate that salivary electrolyte composition may be related to cheek cell Na+/H+ antiporter activity and these parameters may be altered in hypertension.

Effects of the beta-adrenoceptor antagonists atenolol and propranolol on human parotid and submandibular-sublingual salivary secretion

The aim of the study was to evaluate the effects of a beta 1-selective (atenolol 50 mg q.d.) and a non-selective (propranolol 80 mg b.i.d.) beta-adrenoceptor antagonists on human stimulated parotid and submandibular-sublingual (SM-SL) gland secretion. A randomized double-blind, placebo-controlled cross-over ("Latin square") design was used in 19 healthy male volunteers. Stimulated parotid and SM-SL saliva were sampled immediately before and 7 days after the start of each treatment period. Stimulation of salivary secretion was achieved by use of a 3% citric acid solution. Plasma concentrations of propranolol and atenolol were determined from blood samples. The salivary secretion of both glands was assessed for flow rate, amylase, lysozyme, and salivary peroxidase activity and for concentrations of total protein, hexosamine, sialic acid, Ca2+, Cl-, K+, Mg2+, Na+, and PO4(3-). In both parotid and SM-SL secretions, the total protein and phosphate concentrations and amylase activity were significantly decreased during the two active treatment periods. In SM-SL gland secretion, there were significant changes in potassium and calcium concentrations during active treatment as compared with baseline, with potassium showing a decreased and calcium an increased concentration. During atenolol treatment, salivary peroxidase activity decreased significantly in SM-SL secretion. In parotid secretion, the hexosamine/total protein ratio decreased and the sialic acid/hexosamine ratio increased during atenolol treatment, which may indicate an effect on protein synthesis. No significant effects on salivary secretion rates were disclosed.

The effect of propranolol on salivary gland function and dental caries development in young and aged rats

Medications commonly used in elderly people cause hyposalivation and are associated with an enhanced prevalence of dental caries. Propranolol (a beta-adrenergic antagonist) is a commonly used antihypertensive agent that is prescribed for long-term use. The purpose of this investigation was to compare the effects of this drug on salivary composition and flow rate, and on caries, in young and aged rats. Forty young (28-day) and 36 aged (20-month) female Sprague-Dawley rats were infected with Streptococcus sobrinus 6715 and fed a cariogenic diet for 28 days. Propranolol was given in high (20 mg/kg/day) and low (10 mg/kg/day) doses via osmotic pumps. Unoperated and desalivated animals served as controls. Smooth-surface caries scores in the young animals receiving propranolol at 20 mg/kg/day were statistically higher than in the young intact rats (p < or = 0.05). Increased smooth-surface and sulcal caries scores were recorded in the aged propranolol-treated animals, but the differences were not statistically significant when compared with those in intact aged animals. Propranolol in aged animals did not affect the amount of alveolar bone loss but increased the risk of development of root caries. Young animals harboured greater populations of Strep. sobrinus and total cultivable flora than did all aged groups except the desalivated group. Salivary flow rates, induced by pilocarpine, were not decreased by the chronic administration of propranolol. Although the total protein concentration in parotid and submandibular saliva from drug-treated animals was reduced, differences were not observed in their SDS-PAGE profile when compared with unoperated animals. The findings demonstrate that chronic use of propranolol reduced the total protein concentration in saliva of all animals, increased caries susceptibility, but did not reduce the stimulated salivary flow rate.