摘要:

SUMMARY1. The possibility that transmission at some non‐adrenergic, non‐cholinergic (NANC) neuro‐effector junctions is mediated by nitric oxide (NO) arose from the discoveries that NO mediated the effects of nitrovasodilator drugs and that endothelium‐derived relaxing factor (EDRF) was NO or a NO‐yielding substance.2. NO donated by nitrovasodilator drugs or formed by endothelial cells activates soluble guanylate cyclase in smooth muscle and the consequent increase in cyclic guanosine monophosphate (cGMP) results in relaxation. The relaxations produced by stimulation of some NANC nerves are also due to a rise in cGMP.3. The biosynthesis of NO by oxidation of a terminal guanidino nitrogen ofl‐arginine is inhibited by someNG‐substituted analogues ofl‐arginine. These substances block EDRF formation by NO synthase and endothelium‐dependent vasodilatation, and the blockade is overcome byl‐arginine4. NANC relaxations in some tissues are blocked byNG‐substituted analogues ofl‐arginine and restored byl‐arginine. Other agents that affect endothelium‐dependent vasodilator responses produce corresponding changes in responses to stimulation of these NANC nerves. Such observations indicate that transmission is mediated by NO: we have termed this mode of transmission nitrergic.5. There is evidence for nitrergic innervation of smooth muscle in the gastrointestinal tract, genitourinary system, trachea and some blood vessels (penile and cerebral arteries).6. The recognition of a mediator role for NO in neurotransmission calls for reconsideration of previously accepted generalizations about mechanisms of transmission.7. Studies on nitrergic transmission will provide new insights into physiological control mechanisms and pathophysiological processes and may lead to n

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Na+influx into cultured vascular smooth muscle cells (VSMC) obtained from spontaneously hypertensive rats (SHR) and from Wistar‐Kyoto rats (WKY) was measured. Na+influx via the Na+/H+exchange system was measured as the rate of22Na+influx into cultured VSMC sensitive to ethylisopropylamiloride (EIPA), a specific inhibitor of the exchange system.2. The total22Na+influx rate in SHR was significantly higher than in WKY (6.08 ±0.16vs4.13±0.09 nmol/min per mg protein;P<0.001;n= 14). The EIPA (1 × 104mol/L)‐sensitive22Na+influx rate in SHR was significantly higher than that in WKY (4.32 ± 0.27vs2.17 ± 0.14 nmol/min per mg protein;P<0.001;n= 14). There was no difference in EIPA‐insensitive22Na+influx between SHR and WKY. The EIPA‐sensitive22Na+influx rate into VSMC was significantly decreased in SHR but not in WKY by the addition of 1 × 10‐4mol/L 1‐(5‐isoquinoline‐sulfonyl)‐methylpiperazine (H‐7), an inhibitor of protein kinase C (PK‐C).3. These results suggest that the increase in Na+influx in SHR may be due to elevation of the Na+/H+exchange activity, and possible involvement of PK‐C in the increased Na+/H+excha

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The mechanism of the antihypertensive effects of n‐3 fatty acids were examined in spontaneously hypertensive rats (SHR) by feeding ‘Max EPA’ fish oil or hydrogenated coconut oil and determining the responses of perfused mesenteric resistance vessels to various contractile agents and peri‐arterial nerve stimulation.2. Fish oil feeding for 4 weeks caused a decrease in the responses to exogenous noradrenaline and electrical nerve stimulations but had no significant effect on vasopressin and KC1 (80 mmol/L) induced contractions.3. These results provide direct evidence for specific attenuation of vascular responses to sympatho‐adrenal stimulation in resistance vessels following fish oil feeding and may account for the antihypertensive effects seen in humans and in some forms of hypertensio

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Malignant hyperpyrexia (MH) is an inherited muscle abnormality that presents clinically as a syndrome of life‐threatening complications during general anaesthesia.2. Propofol is a new sedative hypnotic used for the induction and maintenance of anaesthesia.3. Propofol did not induce MH in five susceptible pigs. Propofol did not induce contracture in isolated MH susceptible muscle but did modify halothane, caffeine and KCl contracture

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00436.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. Intra‐aortic blood pressure was recorded continuously in freely moving genetically hypertensive (LH), normotensive (LN) and low blood pressure (LL) rats of the Lyon strain during two 11 h periods (08:00‐19:00 h). During the first period (control), the animals were left undisturbed and during the second period (stress), a jet of air was applied for 20 min every hour. Urine was collected simultaneously and analysed for its content in norepinephrine and epinephrine.2. The first exposure to the stressor induced larger increases in blood pressure and heart rate in LH than in LN and LL rats. However blood pressure and heart rate responses to the 10 following stressors decreased in LH rats while they remained stable in LN and LL animals.3. Repeated stress exposure induced significant increases in epinephrine excretion in both LN and LL but not in LH rats.4. It is concluded that LH rats exhibit marked cardiovascular habituation to repeated stress. Taken together with the lack of stress‐induced sympathoadrenal activation, this suggests a reduced level of emotional responsiveness in Lyon hypertensive

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00437.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. This study examined whether brain and atrial natriuretic peptides (BNP, ANP) are secreted together through the coronary sinus from the heart, and whether plasma concentrations of BNP and ANP were affected by ergometric exercise in patients with essential hypertension. The effect of temocapril, a potent angiotensin‐converting enzyme (ACE) inhibitior, on plasma concentrations of these peptides was also examined.2. The plasma concentrations of immunoreactive (ir) BNP and ir‐ANP in the coronary sinus in seven patients with ischaemic heart disease during cardiac catheterization were far greater than values with plasma obtained at the same time from the femoral artery.3. The plasma concentrations of ir‐BNP and ir‐ANP increased with exercise and were correlated with each other. Temocapril reduced the blood pressure and slightly (but significantly) decreased the levels of both peptides at rest and during exercise.4. The results suggested that BNP and ANP were secreted together through the coronary sinus from the heart. The secretion was increased by exercise and suppressed by acute ACE inhibition. The increase in these peptides during exercise may reflect a compensatory mechanism against further elevation of blood p

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00438.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARY1. The usefulness of determining the renal handling of endogenous lithium as a marker of proximal tubular sodium reabsorption was assessed in streptozotocin induced diabetes mellitus in the Sprague‐Dawley rat.2. The clearance and fractional excretion of lithium were determined before and following the development of diabetes mellitus, and compared with measurements of proximal tubular reabsorption made directly using micropuncture techniques. Endogenous lithium was measured in order to avoid the toxic tubular effects of exogenously administered lithium salts.3. Although a trend existed for a reduction in the fractional excretion of lithium in diabetic animals (1.8±0.3vs2.4±0.5%;P>0.20), this did not reach statistical significance and did not accurately reflect the change in directly measured tubular Na reabsorption.4. The decrease in proximal tubular Na reabsorption demonstrated in diabetic animals treated with phlorizin was not significantly reflected in the fractional lithium excretion, although again a corresponding trend was evident (1.9 ± 0.8vs0.6 ± 0.2%;P>0.10.5. In summary, the significant alterations in tubular Na handling in diabetes mellitus, previously demonstrated directly using micropuncture techniques, are not reflected in the renal handling of endogenous lithium. This indirect method is inadequate to assess proximal tubular Na transport in experimental diabetes mel

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00439.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1992.tb00440.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY