摘要:

SUMMARY1. Effects of potassium (K) supplementation (100 mEq/day) on urinary sodium (Na) excretion and on the secretion of atrial natriuretic polypeptide (ANP) during salt loading (350 mEq/day) were studied in 12 healthy salt‐resistant normotensives under strictly controlled metabolic ward conditions.2. Urinary volume and Na excretion on the first day of the high salt period (HSP) were significantly greater in the K‐supplemented group (KG) than in the control group (CG).3. There was a significant gain in bodyweight after salt loading in both groups, with a significantly greater gain in CG on the second day of HSP. Haematocrit decreased significantly during salt loading in both groups, the degree of which was significantly greater in CG.4. Plasma norepinephrine decreased significantly during salt loading in both groups, the degree of which was significantly less in KG than in CG. A significant increase in plasma ANP was observed in CG on and after the second day of HSP, while a significant increase in plasma ANP was observed on the fifth day of HSP in KG.5. These findings indicate that K supplementation accelerates diuresis and natriuresis, resulting in moderate suppression of volume expansion induced by salt loading and that this accelerated diuresis and natriuresis is not a result of the action of

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The effect of cimetidine on gallamine‐induced neuromuscular paralysis was evaluated in urethane‐anaesthetized and mechanically ventilated rats.2. Intravenous cimetidine (between 3.2 and 100 mg/kg) produced an immediate and sustained potentiation of gallamine‐induced neuromuscular paralysis.3. Intravenous calcium (0.35 mmol/kg) completely reversed the cimetidine‐induced potentiation of gallamine's effect.4. Cimetidine alone did not produce neuromuscular paralysis.5. Cimetidine did not alter either the serum concentration or the total serum clearance of gallamine.6. Cimetidine thus potentiates the action of gallamine via a pharmacodynamic and not a pharmacokinetic me

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The direct renal effects of endothelin (ET) were studied in eight chronic hypoxic rats (HA) and eight sea level (SL) spontaneously hypertensive rats (SHR).2. After 4 weeks of exposure to simulated 5486 m (18000 ft) hypoxia, all HA rats were in apparently good health, and baseline renal function, except effective renal blood flow, was not significantly different from SL rats.3. Intrarenal arterial administration of ET (600 ng/ kg per h) reduced ipsilateral renal excretion of water, sodium and potassium, glomerular filtration rate and effective renal plasma flow in both SL and HA rats to almost the same extent.4. Administration of ET antiserum, however, increased the renal excretion of water in HA rats.5. It is concluded that ET may play a role in the renal regulation of chronic hypoxic SHR.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Using a small vessel myograph, experiments were performed on rat small mesenteric arteries (and in some cases dog small coronary arteries) to assess the dependence of vasoconstrictor potency (EC50) and maximum response (Emax) on the initial passive conditions and on the mode of recording (i.e. isometric, isobaric or isotonic).2. Maximum active isometric tension development to methoxamine occurred at different points on the passive diameter‐tension curve depending on the origin of the vessel. The point of maximum sensitivity of methoxamine did not coincide with the point of maximum tension development on the passive diameter‐tension curve.3. Vascular reactivity to methoxamine was assessed under isobaric, isotonic and isometric conditions using a new computerized myograph. Methoxamine was significantly more potent, but only by a factor of twofold, when assessed under isometric conditions. In addition, the maximum response to methoxamine, in terms of diameter change, was always greater under isobaric than under isotonic conditions.4. The results show that, in studies comparing vascular reactivity of vasoactive drugs, the results depend, to some extent, on the initial passive conditions selected. In terms of assessing the pharmacological activity of drugs on isolated blood vessels, the use of common isometric recording procedures are adequate. However, the use of isobaric, isotonic and isometric recording procedures have shown the complexities of vascular reactivity which depend on the passive and active properties of the blood vessel. These factors may need to be taken into account when comparing the reactivity of isolated blood vess

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00420.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Renin synthesis and secretion were studied in Balb/ c mice with a denervated left kidney.2. Denervation inhibited renin secretion.3. Denervation reduced the renal renin content.4. Denervation reduced renal renin mRNA.5. Renal denervation inhibits renin secretion by blocking the synthetic system prior to mRNA formation.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The present study investigated the effects of noise stress (100 dB, 1 kHz, 4 h/day, 6 days/ week) on both systolic blood pressure and vascular reactivities in rats exposed to noise for 2 and 4 weeks. The systolic blood pressure was significantly increased after rats were exposed to noise for 4 weeks but not 2 weeks.2. In isolated thoracic aortic rings, the responses to serotonin were enhanced in noise‐treated rats while there were no changes in response to phenylephrine and high K4between noise‐treated and control rats.3. The relaxant responses to endothelium‐dependent vasodilators (A23187 and acetylcholine) in noise‐treated rats were less than those in control rats. The vasodilator responses to acetylcholine were completely abolished by methylene blue or Nω‐nitro‐L‐arginine.4. Responses to the endothelium‐independent vasodilator, nitroglycerin, were not significantly changed after rats were exposed to noise.5. The enhanced response to vasoconstrictors and the attenuation to endothelium‐dependent vasodilators may account for elevations in blood pressure during noise stress. This indicates that the elevation in blood pressure by noise stress may be partly due to the deterioration of en

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Male Sprague‐Dawley rats were made either hyper‐ or hypothyroid with thyroxine or 4‐methyl‐2‐thiouracil, respectively. Bronchial smooth muscle (BSM) contractility and lung cyclic adenosine 3′,5′‐monophosphate (cAMP) content were measured in both conditions.2. Bronchial smooth muscle contractility was significantly weaker in hyperthyroid rats, while the BSM contractility of hypothyroid rats was the same as controls.3. The cAMP content of hyperthyroid rat lungs was similar to controls but was decreased in hypothyroid rats.4. These studies demonstrated that both the hyper‐ and hypothyroid states affect respiration, although the mechanisms involved with different f

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The effects of thyroxine treatment on soleus and extensor digitorum longus (EDL) muscle contractions and their cyclic adenosine 3′,5′‐monophosphate (cyclic AMP) levels were examined in anaesthetized cats.2. Thyroxine treatment decreased the tension of incomplete tetanic contractions of the soleus as well as the EDL muscles. The effect on tension of these muscles was not associated with an increase in the cyclic AMP level of the muscle as is the case with a β2‐adrenoceptor agonist effect.3. The results do not support the involvement of cyclic AMP in the tension depressant effect of thyroxine on contractions of skeletal muscle.4. It is suggested that the muscle weakness and tremor observed in thyrotoxicosis and during administration of β‐adrenoceptor agonists are mediated by different

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00424.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY