Heart rate and arterial pressure variability in the experimental renovascular hypertension model in rats

This study was conducted in one kidney, one clip (1K1C) Goldblatt hypertensive rats to evaluate vascular and cardiac autonomic control using different approaches: 1) evaluation of the autonomic modulation of heart rate (HR) and systolic arterial pressure (SAP) by means of autoregressive power spectral analysis 2) assessment of the cardiac baroreflex sensitivity; and 3) double blockade with methylatropine and propranolol. The 1K1C group developed hypertension and tachycardia. The 1K1C group also presented reduction in variance as well as in LF (0.23 +/- 0.1 vs. 1.32 +/- 0.2 ms(2)) and HF (6.6 +/- 0.49 vs. 15.1 +/- 0.61 ms(2)) oscillations of pulse interval. Autoregressive spectral analysis of SAP showed that 1K1C rats had an increase in variance and LF band (13.3 +/- 2.7 vs. 7.4 +/- 1.01 mmHg(2)) in comparison with the sham group. The baroreflex gain was attenuated in the hypertensive 1K1C (- 1.83 +/- 0.05 bpm/mmHg) rats in comparison with normotensive sham (-3.23 +/- 0.06 bpm/MmHg) rats. The autonomic blockade caused an increase in the intrinsic HR and sympathetic predominance on the basal HR of 1K1C rats. Overall, these data indicate that the tachycardia observed in the 1K1C group may be attributed to intrinsic cardiac mechanisms (increased intrinsic heart rate) and to a shift in the sympathovagal balance towards cardiac sympathetic over-activity and vagal suppression associated to depressed baroreflex sensitivity. Finally, the increase in the LF components of SAP also suggests an increase in sympathetic activity to peripheral vessels. (c) 2008 Elsevier B.V. All rights reserved.

The influence of age on blood pressure evaluation of hypertensive subjects

The aim of this study was to determine whether age influences the concordance between different methods of blood pressure (BP) measurement and ambulatory BP monitoring (ABPM) in hypertensive subjects. We studied two groups: I, individuals younger than 50 years (n = 57), and II, individuals aged 60 years or older (n = 55). They were submitted to the performance of one ABPM, office BP measurements, home BP monitoring (HBPM), and BP measurements at a public health center (PHCBP). Student`s t-test, Fisher`s test and Lin coefficient were calculated. For Group II, systolic and diastolic pressures measured by HBPM were higher than by day ABPM (p < 0.01). The concordance between day ABPM and the other methods was lower for Group II than for Group I. There was a good concordance between systolic day ABPM and office BP, and between systolic ABPM and PHCBP only for Group I (Lin coefficient = 0.71 and 0.73). Group II reported better sleep quality after ABPM (p < 0.05). Considering 24-h ABPM, 52.6% of Group I and 29% of Group II were controlled (p < 0.01). Concluding, there was worse concordance between different methods of BP measurements and day ABPM in the older group, which had lower hypertension control rate and better tolerance of ABPM. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Low-intensity Treadmill Exercise-related Changes in the Rat Stellate Ganglion Neurons

Stellate ganglion (SG) represents the main sympathetic input to the heart. This study aimed at investigating physical exercise-related changes in the quantitative aspects of SG neurons in treadmill-exercised Wistar rats. By applying state-of-the-art design-based stereology, the SG volume, total number of SG neurons, mean perikaryal volume of SG neurons, and the total volume of neurons in the whole SG have been examined. Arterial pressure and heart rate were also measured at the end of the exercise period. The present study showed that a low-intensity exercise training program caused a 12% decrease in the heart rate of trained rats. In contrast, there were no effects on systolic pressure, diastolic pressure, or mean arterial pressure. As to quantitative changes related to physical exercise, the main findings were a 21% increase in the fractional volume occupied by neurons in the SG, and an 83% increase in the mean perikaryal volume of SG neurons in treadmill-trained rats, which shows a remarkable neuron hypertrophy. It seems reasonable to infer that neuron hypertrophy may have been the result of a functional overload imposed on the SG neurons by initial posttraining sympathetic activation. From the novel stereological data we provide, further investigations are needed to shed light on the mechanistic aspect of neuron hypertrophy: what role does neuron hypertrophy play? Could neuron hypertrophy be assigned to the functional overload induced by physical exercise? (C) 2008 Wiley-Liss, Inc.

High-pressure phase diagram of the drug mitotane in compressed and/or supercritical CO(2)

This work provides experimental phase diagram of mitotane, a drug used in the chemotherapy treatment of adrenocortical carcinoma, in compressed and/or supercritical CO(2). The synthetic-static method in a high-pressure variable-volume view cell coupled with a transmitted-light intensity probe was used to measure the solid-fluid (SF) equilibrium data. The phase equilibrium experiments were determined in temperature ranging from (298.2 to 333.1) K and pressure up to 22 MPa. Peng-Robinson equation of state (PR-EoS) with classical mixing rule was used to correlate the experimental data. Excellent agreement was found between experimental and calculated values. (C) 2009 Elsevier Ltd. All rights reserved.

Evaluation of albuminuria and its relationship with blood pressure in dogs with chronic kidney disease

Background Microalbuminuria and hypertension have long been associated with a guarded prognosis in human patients with a variety of diseases. In veterinary medicine, tests for microalbuminuria have been used for detecting early kidney damage, but there is little information regarding its association with high blood pressure in dogs with chronic kidney disease (CKD). Objective The objective of this study was to evaluate albuminuria and its association with arterial hypertension in dogs with CKD. Methods Urinary albumin:creatinine (UAC) ratio, urinary protein:creatinine (UPC) ratio, and systolic blood pressure were determined in 39 clinically healthy dogs and 40 dogs with CKD. Results UAC in dogs with CKD (range, 0.002-7.99; median, 0.38) was statistically different from that of control dogs (range, 0.0005-0.01; median, 0.002). Microalbuminuria (UAC 0.03-0.3) and macroalbuminuria (UAC > 0.3) were detected in 32.5% and 50% of dogs with CKD, respectively. Sixty percent (24/40) of dogs with CKD had systolic pressure >= 180 mmHg; in these dogs, UAC ratio (range, 0.006-7.99; median, 1.72) was significantly higher than in dogs with CKD and systolic pressure < 180 mmHg (range, 0.002-4.83; median, 0.10). Of hypertensive dogs with CKD, those with UPC > 1.0 usually had macroalbuminuria, those with UPC 0.5-1.0 usually had microalbuminuria, and those with UPC < 0.5 usually lacked albuminuria. Conclusions UAC ratio was higher in hypertensive than in normotensive dogs with CKD. Tests designed to detect microalbuminuria may be useful for hypertensive dogs with CKD and a UPC < 1.0 to detect the onset and magnitude of albuminuria. Once macroalbuminuria is overt, the UPC ratio itself can be used for the same purpose.

The impact of stress and anxiety on the pressure pain threshold of myofascial pain patients

The purpose of this study was to evaluate the influence of stress and anxiety on the pressure pain threshold (PPT) of masticatory muscles and on the subjective pain report. Forty-five women, students, with mean age of 19.75 years, were divided into two groups: group 1:29 presenting with masticatory myofascial pain (MFP), according to the Research Diagnostic Criteria for Temporomandibular Disorders and group 2: 16 asymptomatic controls. An electronic algometer registered the pain thresholds on four different occasions throughout the academic year. To measure levels of stress, anxiety and pain, the Beck Anxiety Inventory, Lipp Stress Symptoms Inventory and Visual Analog Scale (VAS) were used. Three-way anova and Tukey`s tests were used to verify differences in PPT between groups, times and sites. Levels of anxiety and VAS were compared using Mann-Whitney test, while Friedman`s test was used for the within-groups comparison at different times (T1 to T4). The chi-squared and Cochran tests were performed to compare groups for the proportion of subjects with stress (alpha = 0.05). Differences in PPT recordings between time (P = 0.001) and sites (P < 0.001) were detected. Higher levels of anxiety and lower PPT figures were detected at T2 (academic examination) (P = 0.001). There was no difference between groups for anxiety and stress at any time (P > 0.05). The MFP group also has shown significant increase of VAS at the time of academic examination (P < 0.001). External stressors such as academic examinations have a potential impact on masticatory muscle tenderness, regardless of the presence of a previous condition such as masticatory myofascial pain.

Influence of the menstrual cycle on the pressure pain threshold of masticatory muscles in patients with masticatory myofascial pain

Objective. The aim of this study was to investigate the influence of the menstrual cycle and oral contraceptive (OC) intake on the pressure pain threshold (PPT) of masticatory muscles in patients with masticatory myofascial pain (MFP). Study design. The sample was composed of 36 women, divided into 4 groups, according to the presence of MFP and the intake of OC (15 patients had MFP [7 taking OC] and 21 were pain-free controls [8 taking OC]). The algometer-based PPT of masseter and temporalis, and the record of subjective pain by visual analog scale (VAS) were determined during 2 consecutives menstrual cycles at 4 phases (menstrual, follicular, periovulatory, and luteal). A 3-way ANOVA for repeated measurements, Kruskal-Wallis, Friedman, and Dunn tests, with a 5% significant level analyzed the data. Results. PPT was significantly lower in MFP patients when compared with controls throughout the experiment (P < .001). The menstrual phases did not influence PPT (P > .05), while the intake of OC seems to raise PPT levels for the left temporalis (P = .01) and right masseter (P = .04). VAS was, in general, higher at the menstrual phase Conclusions. Different phases of the menstrual cycle have no influence on PPT values, regardless of the presence of a previous condition, as masticatory myofascial pain, while the intake of OC is associated with decreased levels of reported pain.