Thirst perception, drinking, arginine vasopressin activity and associated neurohumoral factors

Thirst, drinking, and arginine vasopressin (AVP) secretion are essential correlated osmoregulatory mechanisms that are crucial for normal physiologic function and overall survival of humans. These homeostatic mechanisms require or are operated via complex central and peripheral neural connections with influence from other peptides and hormones including angiotensin II, atrial natriuretic peptide and relaxin. The effectiveness of these mechanisms declines with age, and the consequences manifest during hyperosmotic challenges as decreased thirst and urine concentrating ability. The neurohumoral cascades involved in the physiological response to alterations in fluid and electrolyte balance are examined.Keywords: Thirst perception, drinking, arginine vasopressin, angiotensin II, atrial natriuretic peptide, relaxi

Thirst perception in dehydrated sickle cell disease patients in steady state

Liberal fluid intake is one of the key management strategies in sickle cell anaemia (SCA) patients in steady state, but less work has been done on the desire of patients to drink water. Using the Visual Analogue Scale we studied thirst perception (TP) in 20 euhydrated SCA patients and 28 control (HbA) subjects, as well as during dehydration in 13 SCA patients and 9 HbA subjects. Serum and urine samples were collected and analyzed for Na, K ions, creatinine concentrations and haematocrit and specific gravity of urine were determined. During euhydration, TP was significantly [

Estimation of Plasma Arginine Vasopressin Concentration Using Thirst Perception and Plasma Osmolality Values

Summary: In human, thirst and antidiuretic hormone (ADH) are controlled by similar sensitive osmoregulatory mechanisms such that above a certain osmotic threshold (280-288 mOsm/kg H20) there is a linear relationship between the increase in plasma osmolality and increase in ADH and thirst. The purpose of this study was to estimate plasma arginine vasopressin (PAVP) using thirst perception (TP) and plasma osmolality (POSM) values before and at 60 minutes in control or euhydrate (group A, 0.0 ml/kg body weight of distilled water), hydrated (group B, 7.1ml/kg body weight of distilled water) and dehydrated (group C, 0.0 ml/kg body weight of distilled water) subjects. A total of twenty five (25) subjects between the ages of 18 and 30 years were used for the study. Calculated POSM and TP values were used to estimate the PAVP concentration. Data were presented as Mean ± SEM. Analyses of results were done using ANOVA and Student t-test. The estimated values of PAVP using TP and POSM respectively at baseline levels were similar in euhydrate (2.22+2.00 vs 2.40+2.10 pg/ml), hydrate (2.22+1.34 vs 2.40+1.72 pg/ml) and in dehydrate (7.05+1.70 vs 6.92+1.94 pg/ml). Sixty minutes later, the values remained similar in euhydrate (3.29+2.40 vs 4.16+2.10 pg/ml), hydrate (1.92+1.60 vs 1.79+1.25 pg/ml) and in dehydrate (8.40+1.40 vs 9.20+1.50 pg/ml). The results show that there was a positive relationship between PAVP calculated from TP and POSM values. We therefore concluded that plasma arginine vasopressin concentration may be estimated using thirst perception and/or plasma osmolality values. Estimation of PAVP using plasma osmolar changes affected by glucose and urea may be inappropriate.Keywords: Arginine vasopressin, Thirst perception, Plasma Osmolality

The role of oropharnygeal receptors in thirst perception after dehydration and rehydration

This study examined the effect of drinking and gargling on thirst perception (TP) in 33 young dehydrated female subjects (18-25yrs), using the visual analogue scale (VAS). Group A subjects drank, while group B gargled the fluid provided - 0.0%, 0.9% and 1.8% NaCl (7.0 ml/kg body weight of fluid). The procedure was  alternated two weeks later. All subjects dehydrated for 18 hours prior to the study, and the last 12-hour urine was collected and volume recorded. Subject who provided a 12hr urine volume greater than 400ml was excluded from the study. After recording the baseline TP, and voiding the bladder, drinking/gargling was done within 5 minutes, and the subsequent TPs were recorded at 5 minutes interval for 25 minutes. Blood samples were collected before and at the end of the 30 minutes, when urine volumes were recorded. Drinking (0.0% and 1.8% NaCl) resulted in an initial decrease in thirst perception, which was statistically significant (p<0.05) only up to 10 minutes. Water intake ad libitum (mean ± SEM) at the end of the 30 minutes was statistically significantly lower (p<0.05) only in the group that drank 0.0% NaCl. Gargling on the other hand did not affect TP and water intake throughout the period of study. It can be concluded that drinking, but not  gargling reduces thirst perception irrespective of the tonicity of the fluid as earlier reported (Obika et. al., 2009; Salata et. al., 1987). This study suggests that the oropharyngeal receptors for TP are activated by recurrent stimulation by the act of drinking rather than gargling.Keywords: Dehydration, Rehydration, Oropharyngeal Receptors, Thirst perception, Drinking, Gargling

Thirst perception in dehydrated sickle cell disease patients in steady state

Liberal fluid intake is one of the key management strategies in sickle cell anaemia (SCA) patients in steady state, but less work has been done on the desire of patients to drink water. Using the Visual Analogue Scale we studied thirst perception (TP) in 20 euhydrated SCA patients and 28 control (HbA) subjects, as well as during dehydration in 13 SCA patients and 9 HbA subjects. Serum and urine samples were collected and analyzed for Na, K ions, creatinine concentrations and haematocrit and specific gravity of urine were determined. During euhydration, TP was significantly [P<0.05] higher in male SCA patients compared to the HbA subjects. In females, TP in SCA patient was not statistically significant compared with HbA subjects. After 13 hours of dehydration, TP was significantly [P<0.05] reduced in female. While dehydration increased TP in HbA subjects, it reduced TP in SCA patients. Fluid intakes after dehydration in SCA patients were not significantly different from the control HbA subjects in both male and female. It can be concluded that female SCA patients do not have normal response to dehydration with regards to TP after a period of dehydration. Since dehydration stimulates the release of vasoactive hormones like vasopressin, this may explain why female patients are less prone to crisis than their male counterparts