Biomedical subjects

L E Nery

Publications and source records attributed to L E Nery.

At least 19 recordsLinked to original sources

PubMed2001

Acute effect of nasal continuous positive air pressure on the ventilatory control of patients with obstructive sleep apnea.

BACKGROUND: Sleep fragmentation can decrease the awake ventilatory control. Since patients with obstructive sleep apnea (OSA) patients exhibit sleep fragmentation linked to respiratory events, their ventilatory control could be impaired. However, most of these patients are also obese, which could conversely increase the ventilatory control. The effect of nasal continuous positive airway pressure (CPAP) on the awake ventilatory control in normocapnic OSA patients is unclear. OBJECTIVES: To study the acute effect of nasal CPAP on the awake ventilatory control in normocapnic OSA patients. METHODS: 12 normocapnic OSA patients, with an apnea/hypopnea index (AHI) >15 with moderate obesity (body mass index: 33.5 kg/m2) and normal pulmonary function tests were submitted to two polysomnography studies (diagnostic and for CPAP titration). Before and after 3 consecutive nights of nasal CPAP we analyzed the hypersomnia score and the ventilatory and the mouth occlusion pressure (P.1) responses at rest (breathing room air and a mixture of 8% CO2 + 40% O2). RESULTS: The respiratory drive of OSA patients as evaluated by P.1 was in the range of the controls of our laboratory. After nasal CPAP, a significant decrease in AHI (mean: 51.9-9.4/h) and arousal (mean: 88.7-43/h) occurred, as well as improvement in nocturnal oxyhemoglobin. There was a marginal increase in DeltaV(E)/DeltaP(ET)CO2 (mean: 1.41-1.87 liters/min/ mm Hg, p = 0.09) and a significant rise in P.1/DeltaP(ET)CO2 (mean: 0.29-0.43 cm H2O/mm Hg), a better indicator of ventilatory drive. CONCLUSIONS: Normocapnic OSA patients increased their awake ventilatory drive response to a hypercapnic and hyperoxic mixture with the use of 3 consecutive nights of nasal CPAP.

Female↗

PubMed2000

The effect of age on the power/duration relationship and the intensity-domain limits in sedentary men.

The time to fatigue (t) in response to high-intensity constant-load exercise decreases hyperbolically with increasing power (W), at least in active and younger individuals [i.e. (W - thetaF)t = W', where thetaF is the critical power asymptote and W' is the curvature constant]. Little is known, however, about the combined effects of age and sedentarity on these parameters. We therefore evaluated 17 non-trained males (9 aged 60-75 years and 8 aged below 30 years) who underwent ramp-incremental cycle ergometry and, on different days, 4 high-intensity constant-load tests to t. Compared to their younger counterparts, the older subjects presented significantly lower maximum oxygen uptake (i.e. the maximum value of oxygen uptake attained at the end of a progressive exercise with the subject exerting a presumably maximal effort, muVO2), estimated lactate threshold (VO2thetaL), VO2thetaF, and W' (P < 0.05). Interestingly, however, both VO2thetaL and VO2thetaF, when expressed as a percentage of muVO2, were higher in older than in younger men [61.8 (6.2)% versus 45.4 (4.6)% and 87.8 (7.3)% versus 79.0 (8.2)%, P < 0.05, respectively]. Therefore, age was associated with an increase in the relative magnitude of the "moderate", sub-thetaL exercise-intensity domain (+30.4%), mainly at the expense of the "very-heavy", supra-thetaF domain (-56%). Our results demonstrate that age and sedentarity are associated with: (1) marked reductions in both the aerobic (thetaF) and anaerobic (W') determinants of the W/t relationship, and (2) changes in either the absolute or relative magnitudes of the exercise-intensity domains. These findings are consistent with the notion that endurance-related parameters are less diminished with ageing than the maximal capacity, thereby mitigating the deleterious effects of senescence in the functional capacity.

Adult↗

PubMed2000

Oxygen cost for cycling as related to leg mass in males and females, aged 20 to 80.

In order to evaluate the determinants of the metabolic cost for cycle ergometry, we analyzed the relationship between VO2 and leg mass (LM) and total body mass (TBM) in 71 randomly-selected sedentary subjects (34 men), aged 20 to 80. Participants performed constant work rate (WR) tests at 0, 25, and 50 W (at 60 rpm) for 6 minutes in a randomized sequence: gross VO2, gross efficiency, and work efficiency were related to TBM and LM as assessed by dual energy x-ray absorptiometry. We found that gross VO2 and gross efficiency were more strongly related to LM than TBM but work efficiency values were independent of both (P>0.05). Significantly higher values of VO2TBM were found in subjects with large LM/TBM ratios and vice-versa; VO2/LM, however, did not change with anthropometric characteristics. Gross VO2 (mL/min) was predicted by a LM-based equation (10.6 [WR, W] + 16.8 [LM, kg] +75) with a mean error below 5%: this equation predicted the cost more accurately than previous TBM-based formulations (P<0.01). We conclude that leg mass actually provides the preferred frame of reference for predicting the oxygen cost for cycle ergometry at 60 rpm in sedentary subjects, independent of age or gender.

Absorptiometry, Photon↗

PubMed2000

Determinants of the exercise endurance capacity in patients with chronic obstructive pulmonary disease. The power-duration relationship.

To characterize the determinants of the power-duration (W-t) relationship in patients with chronic obstructive pulmonary disease (COPD), we evaluated 8 nonhypoxemic patients (FEV(1) = 1.27 +/- 0.26 L) and 10 healthy controls. After an initial maximum-incremental exercise test on cycle ergometer (peak), the subjects underwent four high-intensity constant-load tests to the limit of tolerance (t), each on different days. The W-t relationship was found to be hyperbolic in both groups. Absolute values of both the critical power asymptote (theta(F)) and the curvature constant (W') were lower in patients than in control subjects. However, when expressed as percentage of peak work rate theta(F) was significantly higher in patients compared with control subjects (81.8 +/- 3.3% versus 67.5 +/- 3.7%, respectively, p < 0.01). There were severe reductions in t in the patients that were consistently associated with higher breathlessness scores and V E/MVV ratios. Interestingly, all patients were able to sustain exercise at theta(F) for 20 min despite near-maximum physiological and subjective stresses. We conclude that the reductions of both parameters of the hyperbolic W-t relationship (theta(F) and W') in patients with COPD were due to the ventilatory constraints and their sensory consequences. Importantly, theta(F) separated a "sustainable" from a "nonsustainable" exercise-intensity domain: this parameter consistently occurred closer to peak work rate in patients than the healthy control subjects.

Aged↗

PubMed2000

Comparison of AutoSet and polysomnography for the detection of apnea-hypopnea events.

The use of the flow vs time relationship obtained with the nasal prongs of the AutoSettrade mark (AS) system (diagnosis mode) has been proposed to detect apneas and hypopneas in patients with reasonable nasal patency. Our aim was to compare the accuracy of AS to that of a computerized polysomnographic (PSG) system. The study was conducted on 56 individuals (45 men) with clinical characteristics of obstructive sleep apnea (OSA). Their mean (+/- SD) age was 44.6 +/- 12 years and their body mass index was 31.3 +/- 7 kg/m2. Data were submitted to parametric analysis to determine the agreement between methods and the intraclass correlation coefficient was calculated. The Student t-test and Bland and Altman plots were also used. Twelve patients had an apnea-hypopnea index (AHI) <10 in bed and 20 had values >40. The mean (+/- SD) AHI PSG index of 37.6 (28.8) was significantly lower (P = 0.0003) than AHI AS (41.8 (25. 3)), but there was a high intraclass correlation coefficient (0.93), with 0.016 variance. For a threshold of AHI of 20, AS showed 73.0% accuracy, 97% sensitivity and 60% specificity, with positive and negative predictive values of 78% and 93%, respectively. Sensitivity, specificity and negative predictive values increased in parallel to the increase in AHI threshold for detecting OSA. However, when the differences of AHI PSG-AS were plotted against their means, the limits of agreement between the methods (95% of the differences) were +13 and -22, showing the discrepancy between the AHI values obtained with PSG and AS. Finally, cubic regression analysis was used to better predict the result of AHI PSG as a function of the method proposed, i.e., AHI AS. We conclude that, despite these differences, AHI measured by AutoSettrade mark can be useful for the assessment of patients with high pre-test clinical probability of OSA, for whom standard PSG is not possible as an initial step in diagnosis.

Adolescent↗

PubMed1999

Possible role of non-classical chromatophorotropins on the regulation of the crustacean erythrophore.

Two neuropeptides, the pigment dispersing hormone (PDH) and the pigment concentrating hormone (PCH), are well known to respectively promote centrifugal and centripetal granule translocation in the freshwater shrimp Macrobrachium potiuna erythrophores. Herein, we demonstrate for the first time the effects of crustacean non-classical chromatophorotropins on the pigment migration in M. potiuna erythrophores. Although proctolin, 20-hydroxyecdisone (20HE), and melatonin were ineffective, the crustacean cardioactive peptide (CCAP) was a full agonist, inducing pigment dispersion in a dose-dependent manner with EC(50) of 9.5. 10(-7) M. In addition, concentrations of CCAP lower than the minimal effective dose (10(-8) and 10(-7) M) decreased the PCH-induced aggregation, shifting rightward the dose-response curve (DRC) to PCH 2.2- and 29-fold, respectively. Surprisingly, melatonin (10(-7) and 10(-6) M) also shifted to the right 8.7- and 46.5-fold, respectively, the DRC to PCH. In conclusion, our data demonstrate that besides PCH and PDH, CCAP and melatonin also regulate the pigment migration within the crustacean erythrophore. J. Exp. Zool. 284:711-716, 1999.

Animals↗

PubMed1999

Maximal aerobic power and leg muscle mass and strength related to age in non-athlethic males and females.

To investigate the relationships between the age-associated decline in peak oxygen uptake (peak VO2), leg muscle mass (LMM) and leg strength (LS) under the modulating effect of gender and level of physical activity (LPA, as assessed by questionnaire), we evaluated 71 sedentary subjects [males(M):females(F), 34:37], aged 20-80 years. Peak VO2 at maximum cycle ergometry was related to LMM (dual energy X-ray absorptiometry) and LS (isokinetic dynamometry) using both standard (y x x(-1)) and power function ratios (allometry). Absolute values of all variables were higher in males and declined with age (P < 0.01). Differences between the genders disappeared after peak VO2 x LS(-1.46(M)or -1.62(F)) adjustment but remained significant between peak VO2 LMM-(-0.51 (M)or -0.45(F)) and LS LMM- (-091(M) or -1.10(F)) corrected values. Allometric correction of peak VO2 and LS by LMM slowed their age-related declines; the flattening effect however, was more evident in the females. Interestingly, while no age-related decrement in peak VO2 LS(-1) was found, power function ratio values also declined with age, and at a slower rate in females. These findings are consistent with those obtained following a multiple regression analysis using LPA as an independent covariate (P < 0.01). We conclude that using adequate scaling methods and controlling by LPA: (1) no gender differences are observed in peak VO2 adjusted for LS, (2) loss of LS and LMM are important determinants of the age-associated reduction in physical fitness in both genders but (3) age per se has an LS- and LMM-independent influence on the functional decline, although this intrinsic effect of senescence is less pronounced in females.

Adult↗

PubMed1999

Short-term effects of aerobic training in the clinical management of moderate to severe asthma in children.

BACKGROUND: Aerobic training has a number of well known beneficial effects in both normal and asthmatic children. However, the impact of training on the clinical management of the underlying bronchial asthma remains controversial, particularly in the most severe patients. METHODS: Clinical evaluation, spirometric tests, symptom limited maximum exercise testing, and exercise challenge tests were performed in a group of children with stable moderate to severe asthma. Forty two patients (24 boys) aged 8-16 were evaluated twice: before and after supervised aerobic training (group 1, n = 26) and two months apart (untrained group 2, n = 16). RESULTS: Spirometric and maximal exercise variables in the initial evaluation were significantly reduced in group 1 (p < 0.05) but medication and clinical scores and the occurrence of exercise induced bronchospasm (EIB) did not differ between the two groups. Aerobic improvement with training (maximal oxygen uptake and/or anaerobic threshold increment > 10% and 100 ml) was inversely related to the baseline level of fitness and was independent of disease severity. Although the clinical score and the occurrence of EIB did not change after training, aerobic improvement was associated with a significant reduction in the medication score and the daily use of both inhaled and oral steroids (p < 0.05). CONCLUSIONS: Aerobic improvement with training in less fit asthmatic children is related to a short term decrease in the daily use of inhaled and oral steroids, independent of the severity of the disease.

Adolescent↗

PubMed1999

Prediction of metabolic and cardiopulmonary responses to maximum cycle ergometry: a randomised study.

All of the most widely-cited studies for the prediction of maximum exercise responses have utilized either volunteers or referred subjects. Therefore, selection bias, with overestimation of the reference values, is a likely consequence. In order to establish a set of predictive equations for the gas exchange, ventilatory and cardiovascular responses to maximum ramp-incremental cycle ergometry, this study prospectively evaluated 120 sedentary individuals (60 males, 60 females, aged 20-80), randomly-selected from >8,000 subjects. Regular physical activity pattern by questionnaire, body composition by anthropometry and dual energy X-ray absorptiometry (n = 75) and knee strength by isokinetic dynamometry were also assessed. Previously reported equations typically overestimated the subjects' peak oxygen uptake (p<0.05). Prediction linear equations for the main variables of clinical interest were established by backward stepwise regression analysis including: sex, age, knee extensor peak torque, bone-free lean leg mass, total and lean body mass, height, and physical activity scores. Reference intervals (95% confidence limits) were calculated: some of these values differed markedly from those formerly recommended. The results therefore might provide a more appropriate frame of reference for interpretation of the responses to symptom-limited ramp incremental cycle ergometry in sedentary subjects; i.e. those usually referred for clinical cardiopulmonary exercise tests.

Adult↗

PubMed1999

Reference values for lung function tests. I. Static volumes.

Static lung volume (LV) measurements have a number of clinical and research applications; however, no previous studies have provided reference values for such tests using a healthy sample of the adult Brazilian population. With this as our main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, randomly selected from more than 8,000 individuals. Gender-specific linear prediction equations were developed by multiple regression analysis with total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), RV/TLC ratio and inspiratory capacity (IC) as dependent variables, and with age, height, weight, lean body mass and indexes of physical fitness as independent ones. Simpler demographic and anthropometric variables were as useful as more complex measurements in predicting LV values, independent of gender and age (R2 values ranging from 0.49 to 0.78, P < 0.001). Interestingly, prediction equations from North American and European studies overestimated the LV at low volumes and underestimated them at high volumes (P < 0.05). Our results, therefore, provide a more appropriate frame of reference to evaluate the normalcy of static lung volume values in Brazilian males and females aged 20 to 80 years.

Adult↗

PubMed1999

Reference values for lung function tests. II. Maximal respiratory pressures and voluntary ventilation.

The strength of the respiratory muscles can be evaluated from static measurements (maximal inspiratory and expiratory pressures, MIP and MEP) or inferred from dynamic maneuvers (maximal voluntary ventilation, MVV). Although these data could be suitable for a number of clinical and research applications, no previous studies have provided reference values for such tests using a healthy, randomly selected sample of the adult Brazilian population. With this main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, selected from more than 8,000 individuals. Gender-specific linear prediction equations for MIP, MEP and MVV were developed by multiple regression analysis: age and, secondarily, anthropometric measurements explained up to 56% of the variability of the dependent variables. The most cited previous studies using either Caucasian or non-Caucasian samples systematically underestimated the observed values of MIP (P < 0.05). Interestingly, the self-reported level of regular physical activity and maximum aerobic power correlates strongly with both respiratory and peripheral muscular strength (knee extensor peak torque) (P < 0.01). Our results, therefore, provide a new frame of reference to evaluate the normalcy of some useful indexes of respiratory muscle strength in Brazilian males and females aged 20 to 80.

Adult↗

PubMed1999

Reference values for lung function tests. III. Carbon monoxide diffusing capacity (transfer factor).

Carbon monoxide diffusing capacity (DLCO) or transfer factor (TLCO) is a particularly useful test of the appropriateness of gas exchange across the lung alveolocapillary membrane. With the purpose of establishing predictive equations for DLCO using a non-smoking sample of the adult Brazilian population, we prospectively evaluated 100 subjects (50 males and 50 females aged 20 to 80 years), randomly selected from more than 8,000 individuals. Gender-specific linear prediction equations were developed by multiple regression analysis with single breath (SB) absolute and volume-corrected (VA) DLCO values as dependent variables. In the prediction equations, age (years) and height (cm) had opposite effects on DLCOSB (ml min-1 mmHg-1), independent of gender (-0.13 (age) + 0.32 (height) - 13.07 in males and -0.075 (age) + 0.18 (height) + 0.20 in females). On the other hand, height had a positive effect on DLCOSB but a negative one on DLCOSB/ VA (P < 0.01). We found that the predictive values from the most cited studies using predominantly Caucasian samples were significantly different from the actually measured values (P < 0.05). Furthermore, oxygen uptake at maximal exercise (VO2max) correlated highly to DLCOSB (R = 0.71, P < 0.001); this variable, however, did not maintain an independent role to explain the VO2max variability in the multiple regression analysis (P > 0.05). Our results therefore provide an original frame of reference for either DLCOSB or DLCOSB/VA in Brazilian males and females aged 20 to 80 years, obtained from the standardized single-breath technique.

Adult↗

PubMed1999

Reference values for concentric knee isokinetic strength and power in nonathletic men and women from 20 to 80 years old.

STUDY DESIGN: A prospective, controlled, randomized study. OBJECTIVE: To establish reference values for prediction of concentric isokinetic knee strength and power in a sample of nonathletic men and women. BACKGROUND: Adequate interpretation of knee isokinetic strength and power relies on a representative frame of reference. However, none of the most widely cited prediction studies used a randomly selected sample of nonathletic subjects, therefore limiting the clinical application of these studies. METHODS AND MEASURES: We evaluated the concentric right and left knee extensor and flexor peak torque, total work, set total work, average power, and torque acceleration energy (Cybex 6000 System) in 96 healthy subjects (45 men and 51 women, aged 20 to 80), randomly selected from more than 8000 individuals. RESULTS: By stepwise regression analysis, we found that gender, age, weight, height, and regular physical activity explained up to 84% of the variability of the dependent variables: a set of linear prediction equations for strength (at 60 degrees/s) and power (at 300 degrees/s) is provided. CONCLUSIONS: Results from this study might provide a clinically useful frame of reference for interpretation of concentric isokinetic knee strength and power in nonathletic men and women.

Adult↗

PubMed1998

The influence of 6 months of oral anabolic steroids on body mass and respiratory muscles in undernourished COPD patients.

STUDY OBJECTIVE: To evaluate the influence of oral anabolic steroids on body mass index (BMI), lean body mass, anthropometric measures, respiratory muscle strength, and functional exercise capacity among subjects with COPD. DESIGN: Prospective, randomized, controlled, double-blind study. SETTING: Pulmonary rehabilitation program. PARTICIPANTS: Twenty-three undernourished male COPD patients in whom BMI was below 20 kg/m2 and the maximal inspiratory pressure (PImax) was below 60% of the predicted value. INTERVENTION: The study group received 250 mg of testosterone i.m. at baseline and 12 mg of oral stanozolol a day for 27 weeks, during which time the control group received placebo. Both groups participated in inspiratory muscle exercises during weeks 9 to 27 and cycle ergometer exercises during weeks 18 to 27. MEASUREMENTS AND RESULTS: Seventeen of 23 subjects completed the study. Weight increased in nine of 10 subjects who received anabolic steroids (mean, +1.8+/-0.5 kg; p<0.05), whereas the control group lost weight (-0.4+/-0.2 kg). The study group's increase in BMI differed significantly from that of the control group from weeks 3 to 27 (p<0.05). Lean body mass increased in the study group at weeks 9 and 18 (p<0.05). Arm muscle circumference and thigh circumference also differed between groups (p<0.05). Changes in PImax (study group, 41%; control group, 20%) were not statistically significant. No changes in the 6-min walk distance or in maximal exercise capacity were identified in either group. CONCLUSION: The administration of oral anabolic steroids for 27 weeks to malnourished male subjects with COPD was free of clinical or biochemical side effects. It was associated with increases in BMI, lean body mass, and anthropometric measures of arm and thigh circumference, with no significant changes in endurance exercise capacity.

Administration, Oral↗

PubMed1998

Assessment of ventilatory neuromuscular drive in patients with obstructive sleep apnea.

The presence of abnormalities of the respiratory center in obstructive sleep apnea (OSA) patients and their correlation with polysomnographic data are still a matter of controversy. Moderately obese, sleep-deprived OSA patients presenting daytime hypersomnolence, with normocapnia and no clinical or spirometric evidence of pulmonary disease, were selected. We assessed the ventilatory control and correlated it with polysomnographic data. Ventilatory neuromuscular drive was evaluated in these patients by measuring the ventilatory response (VE), the inspiratory occlusion pressure (P.1) and the ventilatory pattern (VT/TI, TI/TTOT) at rest and during submaximal exercise, breathing room air. These analyses were also performed after inhalation of a hypercapnic mixture of CO2 (delta P.1/delta PETCO2, delta VE/delta PETCO2). Average rest and exercise ventilatory response (VE: 12.2 and 32.6 l/min, respectively), inspiratory occlusion pressure (P.1: 1.5 and 4.7 cmH2O, respectively), and ventilatory pattern (VT/TI: 0.42 and 1.09 l/s; TI/TTOT: 0.47 and 0.46 l/s, respectively) were within the normal range. In response to hypercapnia, the values of ventilatory response (delta VE/delta PETCO2: 1.51 l min-1 mmHg-1) and inspiratory occlusion pressure (delta P.1/delta PETCO2: 0.22 cmH2O) were normal or slightly reduced in the normocapnic OSA patients. No association or correlation between ventilatory neuromuscular drive and ventilatory pattern, hypersomnolence score and polysomnographic data was found; however a significant positive correlation was observed between P.1 and weight. Our results indicate the existence of a group of normocapnic OSA patients who have a normal awake neuromuscular ventilatory drive at rest or during exercise that is partially influenced by obesity.

Adult↗

PubMed1998

Differences between remaining ability and loss of capacity in maximum aerobic impairment.

In the evaluation of exercise intolerance of patients with respiratory diseases the American Medical Association (AMA) and the American Thoracic Society (ATS) have proposed similar classification for rating aerobic impairment using maximum oxygen uptake (VO2max) normalized for total body weight (ml min-1 kg-1). However, subjects with the same VO2max weight-corrected values may have considerably different losses of aerobic performance (VO2max expressed as % predicted). We have proposed a new, specific method for rating loss of aerobic capacity (VO2max, % predicted) and we have compared the two classifications in a prospective study involving 75 silicotic claimants. Logistic regression analysis showed that the disagreement between rating systems (higher dysfunction by the AMA/ATS classification) was associated with age > 50 years (P < 0.005) and overweight (P = 0.04). Interestingly, clinical (dyspnea score) and spirometric (FEV1) normality were only associated with the VO2max, % predicted, normal values (P < 0.01); therefore, in older and obese subjects the AMA/ATS classification tended to overestimate the aerobic dysfunction. We conclude that in the evaluation of aerobic impairment in patients with respiratory diseases, the loss of aerobic capacity (VO2max, % predicted) should be used instead of the traditional method (remaining aerobic ability, VO2max, in ml min-1 kg-1).

Disability Evaluation↗

PubMed1997

Cellular signalling of PCH-induced pigment aggregation in the crustacean Macrobrachium potiuna erythrophores.

The cellular system responsible for the transduction of the pigment-concentrating hormone (PCH) signal was investigated in erythrophores of the freshwater shrimp, Macrobrachium potiuna. Dose-response curves to the hormone were determined in the absence and in the presence of several drugs that affect sequential steps of the Ca(2+)-dependent signalling pathway. Additionally, the ability of forskolin to induce pigment dispersion was evaluated. Neomycin sulphate (10(-4) and 10(-3) mol.l-1), trifluoperazine (10(-5) and 10(-4) mol.l-1), 1-(5-isoquinolinesulfonlyl)-2-methylpiperazine (10(-7) and 10(-5) mol.l-1) and okadaic acid (10(-7) mol.l-1) significantly (P < 0.05) decreased the responses to PCH. However, okadaic acid at low concentration (10(-9) mol.l-1) and cyclosporin A (10(-6) and 10(-5) mol.l-1) did not significantly (P > 0.05) affect PCH activity. Forskolin (10(-4) mol.l-1) was able to half-maximally reverse the hormone-induced aggregation. Our results suggest that the pigment-concentrating hormone induces pigment aggregation through a Ca(2+)-dependent pathway with a posteriori phosphatase activation, probably the serine/threonine phosphatase 1.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1997

Pigment cell signalling for physiological color change.

The cellular signalling pathways participating in physiological color change are reviewed, particularly in crustaceans, teleosts, amphibians, and reptiles. This review is an attempt to summarize what is known and to raise some hypotheses about basic questions still to be elucidated. The first picture that emerges from the literature is that the transduction pathways are identical in the various types of chromatophores of a single species, except for the iridophore. The cAMP-dependent pathway has been well conserved throughout evolution: cAMP increase is the pigment dispersion signal whereas the nucleotide decrease leads to granule aggregation. On the other hand, the Ca(-2)-dependent pathways evoke pigment aggregation in teleosts and crustaceans, and dispersion in amphibians and probably reptiles as well. Another interesting point is the ultimate convergence of the signalling pathways of different agonists inducing the same response in one chromatophore type. A hypothesis is raised about why different chromatophores behave differently in the absence of agonists, that is, why some are punctate, whereas others are stellate.

Animals↗