Experiments were performed in C57BL/6J male mice to determine the effects of acetylcholinesterase (AChE) inhibitor pyridostigmine bromide (PB) and stress on cardiovascular function, structure, and apoptosis. Mice were studied for seven days under the following conditions: Controls (osmotic minipump with saline), PB (10 mg/kg/day, minipumps), shaker stress (45 stressors/day, minipump with saline) and PB+Stress combination. AChE activity was significantly reduced in all PB-treated mice. PB caused no changes in 24-h mean arterial pressure (MAP) or heart rate (HR). Stress
increased 24-h MAP on day 1 and 24-h HR on day 7 in both Stress and PB+Stress groups. A significant reduction in the aortic wall thickness/diameter ratio (P <0.05 vs. control) and slightly reduced relative heart weight were observed in the PB group. These effects were blunted by simultaneous stress exposure. Immunochemistry was used to stain for Bax and Bcl-2 (apoptosis markers). There was a four-fold increase in Bax/Bcl-2 ratio in the heart of PB and PB+Stress treated mice while an attenuation was observed in aortic endothelium. Results suggest that a relatively short-term continuous PB exposure may have adverse effects on the heart and blood vessels, independently of changes in MAP and HR.
Insulin resistance is present in patients with Type 2 diabetes mellitus as well as in obese patients without diabetes. The aim of our study was to compare insulin action in diabetic and control persons with or without obesity and to evaluate the influence of serum cholesterol, serum triglyceride and blood pressure on metabolic variables of insulin action. We examined 42 Type 2 diabetic patients and 41 control persons with body mass index (BMI) from 21.1 to 64.5 kg.m-2, and 33 to 71 years old. The isoglycemic hyperinsulinemic clamp technique was performed at an insulin infusion rate of 1 mU.kg-1.min-1 during 120 min. We evaluated the metabolic clearance rate of glucose (MCRG, ml.kg-1.min-1) as the most important indicator of insulin action by isoglycemic clamp. The Pearson's correlation and multiple regression models were used to compare studied factors with the insulin action. We found following predictors of insulin resistance expressed in the relationship with MCRG: BMI (r = -0.68, p<0.001), plasma glucose concentration (r = -0.66, p<0.001), cholesterol (r=-0.55, p<0.001), triglycerides (r = -0.54, p<0.001) and mean blood pressure (r = -0.38, p<0.01). From the multiple regression analysis we conclude that obesity may have even greater influence on the insulin action than diabetes mellitus itself., G. Šindelka, J. Škrha, M. Prázný, T. Haas., and Obsahuje bibliografii
A hemodynamic feature of chronic sinoaortic
-denervated (SAD)
rats is the increase in blood pressure variability (BPV) without
significant change
s in the average level of blood pressure (BP).
The current study
was designed to
investigate the changes in BP
V- shaped waves (V waves) in SAD rats. Sprague
-Dawley (SD)
rats were divided into
2 groups: SAD rats and sham
-operated
rats (n=13
). Hemodynamics measurements were obtained in
conscious, freely moving rats, four weeks after sinoaortic
denervation or sham operation. V wave indices were evaluated in
rats in both conscious and quiet states.
Additionally, n
ormal and
high BPV was simulate
d by the production of V waves with
different amplitudes. The results showed that the V wave
amplitude was dramatically increased, with a significantly
prolonged duration and reduced frequency in SAD rats
. V wave
BPV in SAD
rats
was significantly increased
, though BP remained
unchanged. The twenty
-four hour BPV in all rats was positively
correlated with amplitude, duration time and V wave BPV and
negatively correlated with frequency. The systolic
BP spectral
powers in the low frequency range (0.38
-0.45
Hz)
were
significantly reduced in the V waves of SAD rats. Moreover, there
was a remarkable increase in mean BPV and a normal mean BP
after simulating high BPV in SAD rats
. The
se results
suggest that
enhancement of V waves might be a waveform character of BP in
SAD rats in both the conscious and quiet states. These types of
V waves appear to be related to a depression of sympathetic
regulation of BP induced by sinoaortic
denervation.
The aim of this study was to ascertain the persistence of heart rate and blood pressure oscillations at the onset of voluntary apnea in humans and to assess the dependence of the fluctuations` parameters on the chemoreceptor activity. In 24 young subjects (10 males, 14 females, mean age 20.4 years) heart rate (represented by its reciprocal value - RR-intervals), systolic blood pressure (SBP) and diastolic blood pressure (DBP) during controlled breathing (CB) of atmospheric air and oxygen followed by apnea were recorded continuously. The cosine functions were then fitted by nonlinear regression analysis to the heart rate, SBP and DBP oscillations during CB and at the onset of apnea. The parameters of oscillations were different during atmospheric air breathing compared to oxygen breathing. During oxygen breathing there was an increase of the RR-interval oscillations - relative bradycardia and enhanced magnitude of respiratory sinus arythmia. During apnea, the base level of the blood pressure oscillations was higher after breathing of atmospheric air compared o oxygen breathing. At least one cosine-like wave oscillation was present at the onset of apnea in the heart rate, SBP and DBP and the second wave was present in all assessed parameters in at least 70 % of recordings. The oscillations in RR-intervals are, to some extent, independent of blood pressure oscillations. No significant gender differences were found either in the duration of breath holding or in the RR and SBP oscillations parameters., M. Javorka, I. Žila, K. Javorka, A. Čalkovská., and Obsahuje bibliografii
It has been shown that endothelium-derived nitric oxide (NO) plays an important role in regulation of vascular tone in the prenatal and early postnatal period. The aim of this paper was to determine the reactivity and accompanying structural changes in thoracic aorta from 4-week-old spontaneously hypertensive rats (SHR) and rats with hereditary
hypertriglyceridemia (hHTG) in comparison with age-matched normotensive controls. For functional studies thoracic aorta was excised, cut into rings and mounted in organ baths for measurement of isometric contractile force. For morphological studies cardiovascular system of rats was perfused with glutaraldehyde fixative (at 100 mm Hg) via cannula placed in the left ventricle. Morphological changes of thoracic aorta were measured using light microscopy. Systolic blood pressure (SBP) in SHR (98±1 mm Hg) did not significantly differ from that of age-matched control rats (95±4 mm Hg), but was slightly increased in hHTG rats (110±2 mm Hg, P<0.05). Heart weight/body weight ratio was higher in SHR and hHTG rats than in control group indicating the hypertrophy of the heart in both models of hypertension. Endothelium-dependent relaxation of aorta induced by acetylcholine was preserved in all groups and did not differ from that in control normotensive rats. The maximal isometric contraction of thoracic aorta to noradrenaline (NA) was reduced in hypertensive groups and the concentration-response curves to NA were shifted to the right indicating increased sensitivity of smooth muscle to NA. The values of wall thickness and cross sectional area as well as inner diameter of thoracic aorta in SHR and hHTG rats were significantly decreased in comparison to control groups. Endothelial dysfunction seems to be absent in all young rats before development of hypertension. In conclusion, our observations indicate that in early stage of experimental hypertension NO-dependent relaxation is preserved so that putative impairment of this function provides no significant pathogenic contribution to the onset of hypertension in these two experimental models.
An ethanol vapor concentration of 1.6 mmol/l was used to test the diurnal variations of the olfactory response in two groups of snails, which were adapted to different light-dark cycles. The results revealed that the olfactory sensitivity to stimulation with ethanol was significantly increased during the day-time, which corresponds to the scotophase of the light-dark cycle, to which the animals had been adapted (c2-test, P < 0.01)., M. Voss, C. Büchert, C. Missfelder., and Obsahuje bibliografii
Cardiovascular effects of LVV-hemorphin-7, a member of the family of fragments from β-chain of human or bovine hemoglobin, were studied in conscious spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats by radiotelemetry. Intraperitoneal injection of hemorphin in a dose of 100 g/kg significantly decreased blood pressure in SHR, whereas negligible effect was seen in normotensive WKY rats. Blood pressure changes were accompanied by reduction of heart rate. In conclusion, a direct effect of LVV-hemorphin-7 on blood pressure was demonstrated in SHR. These biologically active peptides could be involved in blood pressure regulation especially in hypertensive rats, but the precise mechanism should be elucidated.
Impaired glomerular filtration rate (GFR) is a risk factor for the development of hypertension in patients with autosomal dominant polycystic kidney disease (ADPKD). However, markers of tubular function were not tested whether they are linked to hypertension or blood pressure (BP) level. The aim of our study was to investigate the relationship between renal concentrating capacity and BP in children with ADPKD. Fifty-three children (mean age 11.84.4 years) were investigated. Standardized renal concentrating capacity test was performed after nasal drop application of desmopressin, BP was measured by ambulatory BP monitoring (ABPM). Renal concentrating capacity was decreased in 58 % of children. The prevalence of hypertension was significantly higher in children with decreased renal concentrating capacity (35 %) than in children with normal renal concentrating capacity (5 %) (p0.05). Significant negative correlations were found between renal concentrating capacity, ambulatory BP and number of renal cysts (r = –0.29 to
–0.39, p0.05 to p0.01). In conclusion, the concentrating capacity is decreased in about half of the patients and is linked to BP. Decreased renal concentrating capacity should be considered as an early marker of functional impairment in ADPKD and a further risk factor for hypertension.
The insertion of mouse renin gene (Ren-2) into the genome of
normotensive rats causes a spontaneous rise of blood pressure
(BP), leading to an angiotensin II (Ang II)-dependent form of
hypertension in transgenic (mRen-2)27 rats (TGR). However,
enhanced sympathetic BP component was demonstrated in
heterozygous TGR aged 20 weeks. In the present study we used
another model, i.e. Cyp1a1-Ren-2 transgenic rats (iTGR) in which
hypertension can be induced by natural xenobiotic indole-3
carbinol (I3C) added to the diet. We investigated whether the
development of high blood pressure (BP) in 5-month-old iTGR
animals fed I3C diet for 10 days is solely due to enhanced
Ang II-dependent vasoconstriction or whether enhanced
sympathetic vasoconstriction also participates in BP maintenance
in this form of hypertension. Using acute sequential blockade of
renin-angiotensin system (RAS), sympathetic nervous system
(SNS) and NO synthase (NOS) we have demonstrated that the
observed gradual increase of BP in iTGR fed I3C diet was entirely
due to the augmentation of Ang II-dependent BP component
without significant changes of sympathetic BP component. Thus,
the hypertension in iTGR resembles to that of homozygous TGR
in which high BP was entirely dependent on Ang II-dependent
vasoconstriction. Moreover, our measurements of acute BP
response to Rho kinase inhibitor fasudil in animals subjected to
a combined blockade of RAS, SNS and NOS indicated the
attenuation of basal calcium sensitization in both iTGR and
homozygous TGR.