The heritability of circulating testosterone, oestradiol, oestrone and sex hormone binding globulin concentrations in men: the Framingham Heart Study.

OBJECTIVE: Circulating testosterone, oestradiol and oestrone concentrations vary considerably between men. Although a substantial proportion of this variation may be attributed to morbidity and behavioural factors, these cannot account for its entirety, suggesting genetic inheritance as a potential additional determinant. The analysis described here was intended to estimate the heritability of male circulating total testosterone (TT), calculated free testosterone (cFT), oestrone (E1), oestradiol (E2) and sex hormone binding globulin (SHBG), along with the genetic correlation between these factors. DESIGN: Cross-sectional, observational analysis of data from male members of the Offspring and Generation 3 cohorts of the Framingham Heart Study. Data were collected in the years 1998-2005. PARTICIPANTS: A total of 3367 community-dwelling men contributed to the analysis, including 1066 father/son and 1284 brother pairs among other family relationships. MEASUREMENTS: Levels of serum sex steroids (TT, E1 and E2) were measured by liquid chromatography-tandem mass spectrometry, SHBG by immunofluorometric assay and cFT by mass action equation. Heritability was obtained using variance components analysis with adjustment for covariates including age, diabetes mellitus, body mass index and smoking status. RESULTS: Age-adjusted heritability estimates were 0·19, 0·40, 0·40, 0·30 and 0·41 for cFT, TT, E1, E2 and SHBG, respectively. Adjustment for covariates did not substantially attenuate these estimates; SHBG-adjusted TT results were similar to those obtained for cFT. Genetic correlation coefficients (ρG ) indicated substantial genetic association between TT and cFT (ρG = 0·68), between TT and SHBG (pG = 0·87), between E1 and E2 (ρG = 0·46) and between TT and E2 (ρG = 0·48). CONCLUSION: Circulating testosterone, oestradiol and oestrone concentrations exhibit substantial heritability in adult men. Significant genetic association between testosterone and oestrogen levels suggests shared genetic pathways.

Clinical correlates of sex steroids and gonadotropins in men over the late adulthood: the Framingham Heart Study.

Low serum concentrations of sex steroids and gonadotropins in men have been associated with increased cardiometabolic risk and mortality, but the clinical correlates of these hormones in men over late adulthood are less clearly understood. We analysed up to five serial measurements of total testosterone (TT), dehydroepiandrosterone sulphate (DHEAS), follicle stimulating hormone (FSH), luteinizing hormone (LH) and total estradiol (EST) in older men in the original cohort of the Framingham Heart Study to determine the short- (2-years; 1,165 person-observations in 528 individuals) and long-term (up to 10-years follow-up; 2520 person-observations in 835 individuals with mean baseline age: 71.2 years) clinical correlates of these sex steroids and gonadotropins using multilevel modelling and Generalized Estimating Equations. Age, body mass index and pre-existing type 2 diabetes were inversely related to long-term TT concentrations, whereas higher systolic blood pressure showed a positive association. Furthermore, age and pre-existing cardiovascular disease (CVD) were inversely associated and HDL cholesterol concentrations positively associated with long-term DHEAS concentrations respectively. Analyses of short-term changes revealed age was inversely related to DHEAS, but positively related to FSH and LH concentrations. Our community-based study identified modifiable correlates of decreasing TT and DHEAS concentrations in elderly men, suggesting that maintenance of a low CVD risk factor burden may mitigate the age-related decline of these hormones over the late adulthood.

Lipomatosis-associated inflammation and excess collagen may contribute to lower relative resting energy expenditure in women with adiposis dolorosa.

BACKGROUND: Adiposis dolorosa (AD) is a syndrome of obese and non-obese individuals whose hallmark is lipomatosis: unencapsulated painful fatty masses in subcutaneous fat. Lipomatosis may contain excess collagen and multi-nucleated giant (MNG) cells. Case reports suggest metabolic defects in AD. OBJECTIVES: (1) To determine whether women with AD have altered relative resting energy expenditure (REE per total body mass) compared with controls; and (2) to quantitate lipomatosis-associated collagen, MNGs and tissue and blood cytokines that may influence REE. METHODS: A total of 10 women with AD were compared with age, body mass index, fat and weight-matched control women. Adipose tissue was obtained from five women with AD and five controls and evaluated for collagen and macrophages/MNGs. Fat mass and fat-free mass were identified by dual X-ray absorptiometry. REE was by determined indirect calorimetry and related to mass. Adipokines and cytokines were evaluated in blood and tissue. RESULTS: Relative REE (REE per total body mass) was lower in women with AD compared with controls (P=0.007). Only lipomatosis (group) and total body mass were significant predictors of REE in forward stepwise regression (P<0.0001). Adipose interleukin (IL)-6 levels were elevated (P=0.03) and connective tissue was increased fourfold in lipomatosis compared with control tissue (P <0.0001). There was no difference in adipose tissue macrophages between groups; 30% of women with AD had MNG cells. Anti-inflammatory IL-13 levels were elevated (P=0.03), and cytokines important in the recruitment of monocytes, Fraktalkine (P=0.04) and macrophage inflammatory protein-1beta (P=0.009), were significantly lower in the blood of women with AD compared with controls. CONCLUSIONS: The lower relative REE in women with AD compared with controls was associated with increased connective (non-metabolic) tissue in the lipomatosis, and inflammation, although underlying metabolic defects may be important as well. Understanding the pathophysiology and metabolism of lipomatosis in AD may contribute to a better understanding of metabolism in non-lipomatosis obesity.

Insulin improves the endothelium-independent relaxation and the contractile response in aorta from hypertensive diabetic rats.

We investigated the effect of insulin on basal tone and contractile response in isolated aorta from hypertensive streptozotocin-induced diabetic rats (DR) and the role of endothelium in this response. The effect of insulin was tested in rings of control rats (CR) and DR in different protocols: in basal tone, in the plateau of norepinephrine (NE) or KCl contracted rings and in the response to NE or KCl preincubated with insulin. The role of nitric oxide (NO) on insulin response was investigated in rings treated with L-NAME. We found in DR: a) An endothelium independent-vasorelaxant effect of insulin on basal tone; b) A decreased response to NE (without differences in the sensibility) and to KCl (20 mmol/l) and an improvement of this hyporeactivity by insulin pre-treatment, and c) A potentiated vasorelaxant response of insulin dependent of increased vascular tone. Furthermore, an additional action of insulin on endothelial response through NO-release was observed in precontracted vessels from CR, not observed in DR. Our results support that insulin plays a role in regulation of arterial basal tone from DR by a direct effect on smooth muscle vascular cells exposed to high blood pressure. The vasorelaxant effect of insulin dependent of endothelium is blunted in DR by a reduced endothelial NO production. Our work also suggest that insulin could improve the endothelial function in vessels with increased tone in absence of diabetes.

Effects of frog-skin angiotensin II in amphibians.

The role of frog-skin angiotensin II (AII) in amphibia was studied by comparing the sodium and water permeability effects of three angiotensins (AII): frog skin (Ala-Pro-Gly-[Ile3, Val5]-Ang II), human [( Asp1, Ile5]-AII), and Japanese goosefish [( Asn1-Val5]-AII). Frog-skin AII increased the short-circuit current (SCC) significantly after it was added to the dermal side of the isolated skin of the South American frogs, Leptodactylus chaquensis and ocellatus, and the toad, Bufo arenarum, in concentrations of 10(-6) M. In frogs, the effect was significant at 15 minutes and reached 45% over control after 2 1/2 hours. The effect cannot be achieved with concentrations lower than 10(-7) M. Since amiloride (10(-4) M) blocked the SCC response, and absence of chloride in the bathing fluid did not, the effect is probably dependent on sodium transport. Human AII (10(-6) M) produced a similar response in summer frogs that had been treated with 0.1% NaCl for 14 days. Goosefish AII was ineffective at similar concentrations, and none of the angiotensins modified SCC in the toad bladder. Hydrosmotic effects could be achieved with the three angiotensins, the response being dependent on seasonal and species factors but always considerably lower than that of the neurohypophyseal peptides. Vascular reactivity of the isolated frog hindlimbs was compared by dose-response curves. Potency ratios on a molar basis against frog-skin AII was 1.136 for human AII and 1.193 for goosefish AII. The results show that the effects of the angiotensins differ in both the response of SCC to frog-skin angiotensin and its higher vascular effects.

Synthesis of nonmammalian angiotensins and their comparative pressor properties in dogfish shark, domestic chicken, and rat.

To understand how vertebrates utilize angiotensins during evolutionary development, we undertook studies to synthesize and/or characterize angiotensin-like peptides from nonmammalian species. The present paper describes the synthesis of [Asp1,Val5,Asn9] angiotensin I (bull frog, Rana catesbeiana) (I), [Asn1,Val5,His9] angiotensin I (Japanese goosefish, Lophius litulon) (II), [Asn1, Val5,Asn9] angiotensin I (chum salmon, Oncorhynchus keta) (III), and [Asn1, Val5,Tyr9] angiotensin I (related to native angiotensin in snake, Elaphe climocophora (IV). Pressor properties of these peptides were compared with the peptides isolated from other species and related synthetic analogs in one representative species from three distinct classes of vertebrates: 1) elasmobranchs: spiny dogfish shark; 2) birds: domestic chicken; and 3) mammals: rat. The effect of angiotensins on short circuit current (to compare sodium and water permeability) was studied by adding these on the dermal side of the isolated frog skin. In the rat pressor bioassays, the above peptides possessed, respectively, I, 87.8%; II, 51.5%; III, 65.2%; and IV, 60.3% pressor activity of [Ile5] angiotensin II, which was blocked with a converting-enzyme inhibitor, captopril. In the conscious dogfish shark, the percentage increase of blood pressure based on preinjection level (= 100) in the dorsal aortic pressure was 35% to 60% for [Asp1,Ile5,His9] angiotensin I (human) (3 micrograms/kg), [Asp1,Val5,Ser9] angiotensin I (chicken) (3 micrograms/kg), [Asp1,Ile5] angiotensin II (3.6 micrograms/kg), and [Asn1,Val5] angiotensin II (6 micrograms/kg). Likewise, a 30% to 35% increase in blood pressure was obtained with angiotensin III (3 micrograms/kg), [Ile8] angiotensin II (4.4 micrograms/kg), and [Sar1,Ile8] angiotensin II (9.1 micrograms/kg). [Sar1,Thr8] angiotensin II and [Ile8] angiotensin I did not produce a significant pressor response even at high dose-level (8 micrograms/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Norepinephrine depletion impairs motor recovery following sensorimotor cortex injury in the rat.

Beam-walking in the rat provides a method for investigating the effects of drugs on motor recovery following unilateral injury to the sensorimotor cortex. In the present experiment, the impact of norepinephrine depletion on beam-walking recovery was investigated. Groups of rats were first given either the neurotoxin DSP-4 or saline. Two weeks later, the animals were trained at the beam-walking task. Rats were then subjected to either a unilateral sensorimotor cortex lesion or sham operation. Recovery of beam-walking performance was measured over the next 12 days. Pretreatment with DSP-4 significantly slowed the rate of recovery but did not significantly affect sham-operated rats. Norepinephrine was significantly diminished in both lesioned and sham-operated rats that had been given DSP-4. These results are consistent with the hypothesis that recovery of beam-walking in the rat is mediated, at least in part, through noradrenergic neurons.

Atrial natriuretic peptide relaxes arterial basal tone induced by coarctation hypertension.

We have investigated the vasorelaxant effect of atrial natriuretic peptide (ANP) on isolated non-contracted aorta from coarctation hypertensive rats (HR) and the role of endothelium in this vasorelaxant action. After 7-14 days of surgery, mean blood pressure was higher (P < 0.01) in HR compared with sham operated rats (SR), used as the control. ANP (10(-6) mol/l) significantly lowered basal tone in previously unstimulated HR thoracic aortic rings; however, it had no effect in HR abdominal aorta or in SR abdominal and thoracic aorta. Endothelial destruction potentiated the vasorelaxant effect of ANP on basal tone in HR thoracic aorta. A similar potentiation of the ANP-response was observed by pre-treatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 3 x 10(-4) mol/l) or methylene blue (2 x 10(-5) mol/l) in unrubbed HR thoracic aorta. Treatment with calcium-free Krebs + EGTA (2 x 10(-3) mol/l) + sodium nitroprusside (10(-5) mol/l) or calcium-free Krebs significantly decreased basal tone and abolished ANP-response. These effects were observed only in HR thoracic aorta. Similarly, staurosporine (10(-7) mol/l) and calphostin C (10(-6) mol/l), inhibitors of protein kinase C (PKC), diminished basal tone and abolished the ANP-response in HR thoracic aorta. Acetylcholine (10(-6) mol/l) had a small but significant action on the basal tone of unrubbed HR thoracic aorta. These results demonstrate that ANP has a vasorelaxant effect on aortic basal tone when the vessel is exposed to high blood pressure. Inhibition of ANP effects on basal tone by calcium-free Krebs and PKC antagonists suggests that the HR aorta increases Ca2+-active tone, that modifies the response of vascular smooth muscle to the vasodilating hormone ANP.

Post-lesion administration of the NMDA receptor antagonist MK-801 does not impair motor recovery after unilateral sensorimotor cortex injury in the rat.

Although treatment with N-methyl-D-aspartate (NMDA) receptor antagonists reduce neuronal loss after cerebral infarction and brain trauma in laboratory animals, there is little data concerning the effects of these drugs on behavioral recovery. Because NMDA receptor antagonists impede certain kinds of learning, and because motor recovery after sensorimotor cortex injury in the rat is dependent on post-lesion experience, we hypothesized that treatment with MK-801 after focal brain injury would be detrimental. Groups of rats were first trained to traverse a narrow elevated beam and then subjected a right sensorimotor cortex suction-ablation lesion. In the first experiment, 24 h later, each rat received a single dose of either saline or the NMDA receptor antagonist MK-801 (0.5, 1.0, or 2.0 mg/kg). Beam-walking recovery was measured over the next 12 days. In a second experiment, rats were given 3 doses of MK-801 (0.5 mg/kg) at 24 h intervals beginning 24 h after cortex injury. In a third experiment, lesioned and sham-operated rats were allowed to recover for 12 days and then given MK-801 (0.5 mg/kg). Despite obvious behavioral effects of the drug, there was no overall difference in beam-walking performances among the treatment groups in any of the experiments. If 're-learning' is involved in motor recovery after cortex injury, the present results suggest that the process is not susceptible to permanent disruption by the early or late administration of an NMDA receptor antagonist.

Epidemiology of cholelithiasis in southern Italy. Part II: Risk factors.

OBJECTIVE: To determine behavioural, dietary and other common factors associated with new cases of gallstones, diagnosed by ultrasonography, in a prospective cohort study conducted in southern Italy. SUBJECTS AND METHODS: Between May 1985 and June 1986, systematic sampling from the electoral register of Castellana, a small town in southern Italy, yielded 2472 subjects who had had their gallbladder checked for gallstones by ultrasonography. Between May 1992 and June 1993, 1962 out of the 2235 (87.7%) subjects without gallstones at baseline agreed to a further ultrasound examination. At the first survey a standardized questionnaire was administered, inquiring about medical history, diet, cigarette smoking and other behavioural characteristics. Height and weight were also measured, and blood levels of glucose, cholesterol, HDL-cholesterol and triglycerides were determined by standard methods. The same variables were measured at the second survey. The diagnosis of gallstones was made with the same echograph by echographists working in the same department. Multiple logistic regression was used to determine which factors measured at the first survey were associated with the incident cases of gallstones. RESULTS: One hundred and four subjects had developed gallstones, an incidence of 9.7 per 1000 persons per year. Age, body mass index (BMI), weight change, a history of diabetes, constipation (shown by use of laxatives), cigarette smoking, years of schooling, consumption of fried foods and excessive oil, and pregnancy in females, were positively associated with the incidence of gallstones. Consumption of wine, coffee, fish and wholemeal bread was inversely associated. Sex, family history of cholelithiasis, use of oral contraceptives and serum lipids were not independent risk factors for gallstones. CONCLUSION: The results of this study confirm many gallstone-associated factors reported in previous cross-sectional and case-control studies, as well as in other cohort studies based on the clinical diagnosis of gallstones, such as BMI, ageing and wine consumption. Furthermore, use of laxatives, considered a proxy of constipation, appears to be another important independent risk factor for gallstones.

Measurement of micronuclei by cytokinesis-block method in bovine lymphocytes.

The present study was carried out in order to set up a standardized quantitative assay for spontaneous micronuclei in bovine lymphocytes. For this purpose the cytokinesis-block micronucleus (MN) method, originally proposed by Fenech and Morley (1985) for human lymphocytes, was applied to peripheral blood lymphocytes of 20 healthy cows of Italian Friesian breed. The results demonstrate that the optimal concentration of cytochalasin B to obtain the highest frequency of binucleated cells (mean = 400.26 +/- 23.76/1000 cells scored) was 6 micrograms/ml. The baseline frequency of spontaneous MN formation in 500 binucleated cells was 12.3 +/- 4.1, i.e., 3 times higher than that reported in human lymphocytes (Fenech and Morley, 1985; Scarfi et al., 1991). The possible reason(s) for this difference (sensitivity to cytochalasin B, chromosome number, environmental genotoxic pollutants) is discussed.

Prorenin concentration in the hypertensive disorders in pregnancy.

OBJECTIVE: To evaluate the plasma prorenin levels during the three trimesters of normal pregnancy, their prognostic value, and their correlation with hypertensive disorders of pregnancy. DESIGN: A prospective study in which plasma prorenin and renin levels were measured in 55 healthy pregnant women and 66 who developed gestational hypertension or preeclampsia. The patients were classified as mild preeclampsia (mild PE), severe preeclampsia (severe PE), chronic hypertension and superimposed preeclampsia upon chronic hypertension (superimposed PE). METHOD: Venous blood samples were collected in the first, second and third trimesters and during delivery or cesarean. Plasma renin concentration (PRC) was measured by radioinmmunoassay before and after incubation with trypsin solution. The difference gave plasma prorenin concentration (PProRC). RESULTS: PRC and PProRC were significantly higher in pregnant women compared with healthy non-pregnant. PRC was significantly increased in the first trimester in the chronic hypertension group and a lower value was found in the first trimester in the superimposed PE compared with those in healthy pregnant women. No differences in other groups were found. PProRC showed a significant lower value in the first and third trimesters in the severe PE group. In the superimposed PE a low value of PProRC similar to those of non-pregnant women was found. CONCLUSIONS: The results show that the different types of hypertension in pregnancy have different profiles of PProRC and PRC in relation to development of preeclampsia. The absence of increase of PProRC in the first trimester of superimposed PE may have a prognostic value.

Vascular maternal reactivity and neonatal size in normal pregnancy.

OBJECTIVE: The purpose of the present study was to determine the associations of cold pressor test (CPT) cardiovascular reactivity with gestational age at birth and neonatal size in normotensive pregnant women. METHODS: Seventy (70) healthy pregnant women were enrolled. The CPT consisted of introducing the patients' hands in cold water (4 degrees C) for 3 min. An automatic oscillometric device was used to record blood pressure (BP) every minute for the following 5 min. Perinatal results were correlated with CPT findings. RESULTS: Vascular reactivity assessed by CPT was higher in pregnant hypertensive women and in women with a hypertensive family history. Mean BP increases caused by CPT showed a significant negative correlation for gestational age (r = -0.58, p < 0.001) and cephalic perimeter (r = -0.57, p = 0.03). Diastolic BP increases caused by CPT were negatively correlated with newborn weight (r = -0.78, p < 0.001). Predictable newborn weight, gestational age, and cephalic perimeter were 4046 (47 x diastolic BP increase), 40.2 (0.07 x mean BP increase), and 35.8 (0.09 x mean BP increase), respectively. CONCLUSIONS: Results show that every mm Hg diastolic BP increase in response to CPT was correlated with a 47-g decrease in the newborn normal weight. Furthermore, every mean mm Hg BP increase in response to CPT was associated with a 0.07-week decrease in the newborn normal gestational age and a 0.09-cm decrease in the normal cephalic perimeter at birth.

Alcohol drinking and blood pressure among adolescents.

The purpose of this study was to evaluate alcohol consumption among adolescents from Tucuman, Argentina, and to determine its possible relationship with increased levels of blood pressure. Three hundred fifty-six students aged 13-18 included in the study were asked to answer questionnaires anonymously. Two blood pressures measures were then taken. Differences between both sexes were found in quantity and frequency of alcohol consumption. Enjoyment was determined to be the main reason for drinking. There was an association between frequency and alcohol-related problems, and smoking habits. There were also differences in blood pressure among males and females. A weak, but significant, relationship between quantity/frequency index and diastolic blood pressure was found. A greater prevalence of hypertension in male heavy drinkers was noted as well. Because this addiction implies multiple social problems and it also accounts for a hypertension risk factor, the importance of aiming at developing prevention strategies for alcohol abuse among adolescents is stressed.

Angiotensin-(1-7) increases osmotic water permeability in isolated toad skin.

Angiotensin-(1-7) (Ang-(1-7)) increased osmotic water permeability in the isolated toad skin, a tissue with functional properties similar to those of the distal mammalian nephron. Concentrations of 0.1 to 10 microM were effective, with a peak at 20 min. This effect was similar in magnitude to that of frog skin angiotensin II (Ang II) and oxytocin but lower than that of human Ang II and arginine-vasotocin. The AT2 angiotensin receptor antagonist PD 123319 (1.0 microM) fully inhibited the response to 0.1 microM Ang-(1-7) but had no effect on the response to Ang II at the same concentration. The specific receptor antagonist of Ang-(1-7), A-779, was ineffective in blocking the response to Ang-(1-7) and to frog skin Ang II. The AT1 receptor subtype antagonist losartan, which blocked the response to frog skin Ang II, was ineffective in blocking the response to Ang-(1-7). The present results support the view of an antidiuretic action of Ang-(1-7) in the mammalian nephron.

Synthesis and structural characterization of poly(LGGVG), an elastin-like polypeptide.

Poly(LGGVG) a potential elastin-like biomaterial has been synthesized and studied both in solution (by circular dicroism and nuclear magnetic resonance) and in the aggregated state (by transmission electron microscopy). For sake of comparison, also the conformation of the protected (Boc-LGGVG-OEt) and free (H(2)(+)-LGGVG-OH) 'monomers' has been investigated. While in the latter ones the presence has been evidenced of more or less stable type II beta-turns, the polymer showed a conformational ensemble, possibly comprising type II beta-turns, type I beta-turns and open (unordered) structures. At supramolecular level, twisted-rope aggregates were observed by transmission electron microscopy for the polymer. Thus, the title compound has shown to possess, at both molecular and supramolecular level, physico-chemical properties very similar to those of elastin, so to give some confidence that it could really constitute the precursor of an artificial substitute of elastin itself.

Inhibitory effect of sodium ursodeoxycholate on basal and stimulated short-circuit current across the isolated toad skin.

The effect of sodium ursodeoxycholate (U) on short-circuit current (SCC), an index of basal and stimulated net ion transport across isolated skins of Bufo arenarum toads, was tested. U inhibited basal SCC when added to the epidermal side of the skins. The inhibitory effect was reversible after rinsing the preparation during 60 min. U also inhibited the natriferic response to oxytocin, db-cAMP and theophylline by 82%, 49% and 47%, respectively. Inhibition of SCC by exposure to U was reversed by the polyene antibiotic nystatin. In turn, SCC induced by nystatin in the amiloride-treated skin was insensitive to U and blocked by ouabain, a Na+, K(+)-ATPase inhibitor. These results strongly suggest that the effect of U is exerted at the apical membrane of sodium transporting cells, and rule out the existence of an additional site of inhibitory action of U.

Atrial natriuretic peptide inhibited the natriferic and hydrosmotic effects of arginine vasotocin on toad skin.

The effect of rat atrial natriuretic peptide (rANP) on hormonal stimulated osmotic water permeability (Jw, hydrosmotic effect) and net ion transport (short-circuit current, SCC, natriferic effect) was studied on toad skin, a tissue with functional similarities to the mammalian distal nephron, in order to assess actions on transport mechanisms. Rat atrial natriuretic peptide, rANP-99-126 (rANP) inhibited stimulated SCC and Jw to submaximal concentrations of arginine vasotocin (AVT) at a site before cyclic AMP generation. The angiotensin-converting enzyme inhibitor (ACEI) MK-422 did not modify the inhibitory effect of ANP in the stimulated Jw.

Basal and amiloride-induced short-circuit current across isolated toad skin (Bufo arenarum).

We have previously demonstrated that amiloride (amil) addition to the isolated ventral pelvic (VPel) skin of Bufo arenarum toad induces negative short-circuit current values, which are equivalent to the isotopically measured net chloride transport. In the present work, we found that exposure of various regions of toad skin to amil yielded different values of short-circuit current (aSCC): negative aSCC was found in the VPel and ventral pectoral skin, while those of the dorsal one were not different from zero. The distinct values of aSCC found show a regional difference in the active chloride absorption, probably related to postural adaptations. A possible role of this adaptation would be related to chloride participation in the saline balance of the animals, or the maintenance of epithelial integrity.

Effects of psychological stress on cold pressor test results.

The authors evaluated the incidence of a psychological stressor in the modification of blood pressure induced by the cold pressor test in normotensive and medicated hypertensive subjects. The study was carried out in two stages: In the first, 28 (14 normotensive and 14 hypertensive) subjects were administered a cold pressor test. Fifteen days later, 14 subjects repeated the same experiment. The remaining 14 subjects (7 hypertensive and 7 normotensive) also repeated the cold pressor test, with the difference that, to add a stressful psychological situation, the physician "abandoned" them at the beginning. The addition of the psychological stress significantly increased only systolic blood pressure in both the hypertensive and the normotensive subjects. Furthermore, the hypertensive subjects did not recover their basal blood pressure values following the cold pressor test when the psychologically stressful situation had been added. These results show the importance of considering psychological aspects when applying physical pressor tests.