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  • 1
    Electronic Resource
    Electronic Resource
    HAEMODYNAMIC AND HUMORAL CONSEQUENCES OF CHRONIC INFUSION OF VASOPRESSIN IN CONSCIOUS RATS (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 20 (1993), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. To determine the long-term haemodynamic and humoral effects of arginine vasopressin (AVP), a chronic intravenous infusion of AVP was performed in conscious Wistar normotensive rats.2. AVP (1, 10, 50 or 100 ng/h) or saline as a vehicle control was infused continuously into the right jugular vein at a rate of 1 μL/h using an osmotic minipump for 7 days.3. As a result, significant elevations of systolic blood pressure were observed in association with increases in plasma AVP concentration. Significant decreases in heart rate were observed during infusion of 100 ng/h of AVP. Mean arterial pressures measured directly on the sixth day of infusion were significantly higher in the rats given 50 ng/h (125 ± 3 mmHg) or 100 ng/h (125 ± 2 mmHg) compared with control rats (117 ± 2 mmHg). Intravenous injection of the V1 antagonist, d(CH2)5Tyr(Me)AVP, significantly reduced the elevated mean arterial pressure induced by 50 or 100 ng/h of AVP (—7 ± 4 and—11 ± 2 mmHg, respectively). Plasma renin and norepinephrine concentrations were not affected by AVP infusion, while plasma epinephrine concentration was lower in the rats given 100 ng/h of AVP. Intravenous infusion of AVP did not alter bodyweight, serum electrolytes or osmolality.4. These results suggest that AVP has a long-term pressor effect which is attributable to its vasoconstrictor action in conscious rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1993.tb01730.x
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  • 2
    Electronic Resource
    Electronic Resource
    EFFECT OF EXERCISE ON PLASMA ADRENOMEDULLIN AND NATRIURETIC PEPTIDE LEVELS IN MYOCARDIAL INFARCTION (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 24 (1997), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. We investigated the effect of exercise on plasma adreno-medullin, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations and studied the relationship between these peptides and haemodynamic parameters in nine patients with old myocardial infarction (MI) and in eight normal subjects.2. The exercise protocol consisted of two fixed work loads (40 and 80 W) for 4 min each and venous blood samples were taken at rest, during each exercise stage and after exercise while monitoring the mean arterial pressure (MAP) and heart rate (HR). In MI, pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic pressure (LVEDP) and cardiac output (CO) were measured throughout exercise.3. Adrenomedullin levels did not significantly increase with exercise. Adrenomedullin levels correlated with PAP and PCWP at rest (P 〈 0.05). Atrial natriuretic peptide levels correlated with PAP, PCWP and LVEDP throughout exercise (P 〈 0.05) but, on multiple regression analysis, PCWP correlated only with ANP (P 〈 0.01). Brain natriuretic peptide levels correlated with LVEDP throughout exercise (P 〈 0.01) and its increment correlated closely with basal BNP levels at rest (P 〈 0.01).4. These results suggest that adrenomedullin does not respond to the acute haemodynamic changes of exercise, whereas ANP responds to it and PCWP is the major stimulus factor. Brain natriuretic peptide responds to exercise in proportion to the basal synthesis of BNP in patients with left ventricular dysfunction and LVEDP may play a role in increasing BNP during exercise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1997.tb01194.x
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  • 3
    Electronic Resource
    Electronic Resource
    BRAIN ANGIOTENSIN AND CIRCULATORY CONTROL (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 23 (1996), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Components of the renin-angiotensin system (RAS) are found in the brain; both outside and inside the blood-brain barrier.2. Almost all of the classical actions of the brain RAS are attributable to angiotensin (Ang) II and mediated by AT1 receptors.3. Circumventricular organs (CVO), which lack the blood-brain barrier, are rich in AngII receptors and monitor circulating AngII levels. In vivo binding studies suggest that the CVO are also accessible to cerebrospinal fluid-derived AngII.4. The median preoptic nucleus, paraventricular hypothalamic nucleus, supraoptic nucleus, nucleus tractus solitarius and ventrolateral medulla are inside the blood-brain barrier and are sites of action of brain AngII. In these nuclei, AngII seems to act as an excitatory neurotransmitter or neuromodulator.5. Actions of AngII in the brain, both inside and outside the blood-brain barrier, are implicated in the central regulation of blood pressure and sympathetic outflow, release of hypothalamic and pituitary hormones and renal sodium handling.6. Alterations in the activity of brain AngII may be involved in the mechanisms of some types of hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1996.tb02761.x
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  • 4
    Electronic Resource
    Electronic Resource
    LACK OF SYMPATHETIC AUGMENTATION IN RESPONSE TO INTRAVENOUS LOAD OF GLUCOSE IN RABBITS (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 18 (1991), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. We investigated a link between sympathetic nervous function and carbohydrate metabolism by measuring renal sympathetic nerve activity in response to intravenous load of glucose in α-chloralose-urethane anaesthetized rabbits.2. Intravenous infusion of a 25% glucose solution (0.5 g/kg) over 3 min caused a transient increase in arterial blood pressure and a decrease in renal sympathetic nerve activity. Thereafter, these parameters were restored and remained around preload levels while plasma glucose and insulin concentrations were still elevated.3. Equimolar mannitol solution produced similar patterns of change in blood pressure and nerve activity without an elevation of plasma glucose and insulin levels.4. The transient changes in blood pressure and renal nerve activity could be attributed to acute hypervolaemia indicated by similar changes in plasma osmolality and haematocrits in the two groups of treatment.5. The present study did not support a close relationship between carbohydrate metabolism and the sympathetic nervous system regulating cardiovascular function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1991.tb01487.x
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of air-jet stress on renal blood flow in spontaneously hypertensive rats (1997)
    Springer
    Clinical and experimental nephrology 1 (1997), S. 261-265 
    Details
    ISSN: 1437-7799
    Keywords: psychological stress ; sympathetic nerve activity ; renal blood flow ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background Stressful psychological stimuli produce an increase in renal sympathetic nerve activity (RSNA) and a decrease in renal blood flow. Very few direct analyses of the relationship between RSNA and renal blood flow during the application of psychological stimuli have been conducted by recording these 2 measurements simultaneously in the same individual animals. Methods We simultaneously measured RSNA and renal blood flow as a Doppler shift in conscious, unrestrained, spontaneously hypertensive rats. The rats were stressed by directing a continuous air jet at their faces for 20 seconds. Results Air-jet stimulus increased RSNA 81%±15% (mean±standard error of the mean, n=10), mean arterial pressure (21±3 mm Hg), and renal vascular resistance (37%±6%), and decreased renal blood flow (−15%±2%). The percentage change in RSNA correlated positively with the change in mean arterial pressure (r=0.934,P〈0.001) and percentage change in renal vascular resistance (r=0.912), and negatively with the percentage change in renal blood flow (r=−0.804). The denervation of renal nerves prevented renal blood flow from decreasing in response to air-jet stress. Conclusions A reduction in renal blood flow in response to short-term air-jet stress is elicited mainly by neural mechanisms in spontaneously hypertensive rats. Enhancement of RSNA by air-jet stimulus exerts a potent constricting effect on the renal vascular bed, resulting in a reduction in renal blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02480638
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  • 6
    Electronic Resource
    Electronic Resource
    Neural effects of natural behavior on renal blood flow in spontaneously hypertensive rats (1998)
    Springer
    Clinical and experimental nephrology 2 (1998), S. 234-239 
    Details
    ISSN: 1437-7799
    Keywords: behavior ; renal blood flow ; sympathetic nerve activity ; antihypertensive drug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background In states of stress and exercise, renal blood flow is shown to be depressed, mainly through neural mechanisms. Little is known, however, about the effects of natural or spontaneous behaviors on renal blood flow and renal sympathetic nerve activity. Methods We simultaneously measured renal sympathetic nerve activity and renal blood flow as a Doppler shift during grooming and exploring behaviors in spontaneously hypertensive rats. We also tested the effects of vasodilating drugs on changes in renal blood flow. Results Grooming behavior (n=21) increased renal sympathetic nerve activity, mean arterial pressure, and decreased renal blood flow. Percentage changes in renal sympathetic nerve activity correlated negatively with percentage changes in renal blood flow. Exploring with rearing (n=14) induced similar but larger changes in these variables. Denervation of renal nerves suppressed a reduction in renal blood flow during these behaviors. After intravenous injection of manidipine (a calcium channel blocker) or CV-11974 (an angiotensin II receptor antagonist), the behavior-induced reduction in renal blood flow was significantly smaller than that found before treatment, despite similar increases in renal sympathetic nerve activity. Conclusion Natural behaviors decrease renal blood flow in relation to the enhancement of renal sympathetic nerve activity, which is similar to the responses of the animals to stressful psychologic stimuli. Vasodilating drugs can attenuate the reduction in renal blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02480563
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of intraventricularly injected 6-hydroxydopamine on carotid sinus baroreceptor reflex in rabbits (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 289 (1975), S. 345-358 
    Details
    ISSN: 1432-1912
    Keywords: Baroreceptor Reflex ; Brain Noradrenaline ; 6-Hydroxydopamine ; Phentolamine ; Blood Pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of 6-hydroxydopamine (6-OH-DA) injected into the lateral brain ventricle on the carotid sinus baroreceptor reflex were studied in rabbits anesthetized with α-chloralose and urethane. As short term effects, injection of 500 μg/kg of 6-OH-DA caused a fall in blood pressure and heart rate, enhanced the depressor and bradycardia responses to electrical stimulation of the carotid sinus nerve (CSN), and inhibited the pressor response to carotid occlusion. These effects reached the maximum within 2 hrs and disappeared by the 4th hr. Intraventricular injection of noradrenaline (NA) could mimic most of these effects. At 4.5 hrs after injection of 6-OH-DA, NA content of the brain was definitely reduced: 21% of control in the hypothalamus and 14% in the pons-medulla. Rabbits treated with 6-OH-DA under pentobarbital anesthesia 24 hrs before showed a slight fall in resting blood pressure and almost normal baroreceptor function. Intraventricular application of phentolamine abolished the responses to CSN stimulation in 6-OH-DA pretreated as well as normal animals. These results suggest that the acute effects of 6-OH-DA are based on the increased release of NA from the affected nerve terminals and that noradrenergic neurons are involved in the central pathway of baroreceptor reflex. Moreover, the reflex may be functionally maintained by a small portion of brain NA content, even when noradrenergic neurons are greatly affected by 6-OH-DA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508409
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