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  • 1
    Electronic Resource
    Electronic Resource
    ACETYLCHOLINE-INDUCED SYSTEMIC VASODILATION RESISTANT TO NG-NITRO-L-ARGININE IN ANAESTHETIZED RATS (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 25 (1998), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The effects of NG-nitro-L-arginine (l-NNA; 20mg/kg bodyweight (BW), i.v.) and metyrapone (300 mg/kg BW, s.c.) on acetylcholine (ACh)-induced depressor responses were investigated in anaesthetized rats.2. Acetylcholine (0.05,0.5,5 μg/kg BW, i.v.) dose-dependently evoked a sharp fall in mean blood pressure (BP) followed by a slow recovery under control conditions.3. Basal BP level was elevated when rats were treated with l-NNA, indicating endogenous nitric oxide (NO) participated in BP regulation. However, pretreatment with l-NNA did not attenuate but rather augmented the ACh-induced maximum vasodilation. In contrast, the time for recovery of mean BP to the pre-ACh administration level was shortened by l-NNA. These observations suggested that ACh-induced vasodilation consisted of two phases: a sharp and transient fall (phase 1) that was resistant to l -NNA followed by a longer depressor response (phase 2) that was suppressed by l-NNA.4. To examine whether augmentation of phase 1 by l-NNA resulted from the elevation of basal BP, an appropriate dose of phenylephrine was infused to obtain similar BP elevation. Phenylephrine infusion augmented the phase 1 in a similar manner to l-NNA pretreatment but showed little effect on phase 2, supporting the selective inhibition of phase 2 by l-NNA.5. The s.c. pretreatment with metyrapone for 3 days failed to attenuate phase 1. Thus, the involvement of endothelium-derived hyperpolarizing factor that could be formed by a metyrapone-sensitive oxidase in phase 1 was unlikely.6. These results suggest that some factor(s), which is not inhibitable by l-NNA or metyrapone, may induce the phase 1 depressor response to ACh while NO is responsible for the phase 2 response. The mechanism inducing the phase 1 response remains to be identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1998.tb02244.x
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  • 2
    Electronic Resource
    Electronic Resource
    EFFECT OF NG-M0N0METHYL-L-ARGININE ON THE MICROCIRCULATION OF RAT SKIN (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. The effects of NG-monomethyl-L-arginine (L-NMMA), a nitric oxide (NO) synthase inhibitor, on the microcirculation of rat dorsal skin were studied to examine the role of NO in the regulation of regional haemodynamics.2. The blood volume in the skin microcirculation, which was continuously measured by reflectance spectrophotometry, was significantly decreased in response to L-NMMA (10 mg/kg bodyweight, i.v.), suggesting vasoconstriction, and the response continued for more than 20 min. In contrast, the increase in systemic blood pressure (BP) disappeared soon after administration of L-NMMA.3. These results show that L-NMMA elicits long-lasting responses in the skin microcirculation, whereas the systemic BP rapidly recovers, suggesting a large contribution of the NO system to the regulation of rat skin microcirculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1997.tb01798.x
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  • 3
    Electronic Resource
    Electronic Resource
    COMPARISON OF VASOPRESSOR EFFECTS OF NITRO ARGININE IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS AND WISTAR-KYOTO RATS (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. NG-nitro-L-arginine (NO2Arg) is a guanidine nitro arginine derivative and an inhibitor of endothelium-dependent vascular relaxation. Significant rise of the systolic blood pressure was observed after 1 week administration of NO2Arg in food (0.023% in weight, about 2.8 mg of NO2Arg/rat per day) in female rats of stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). The rises were not different between SHRSP (21 mmHg) and WKY (23 mmHg).2. In ring preparations of the thoracic aorta of NO2Arg-administered rats of both strains, relaxation by acetylcholine decreased markedly compared with those of the control rats (to 43–44%). On the contrary, glyceryltrinitrate-induced relaxation was slightly but significantly increased in the aorta of WKY after NO2Arg administration and the same tendency was observed in SHRSP.3. The rise of blood pressure and the decrease of acetylcholine-induced relaxation suggested that NO2Arg inhibited the endothelium-dependent relaxation not only in WKY but also in SHRSP. The relaxation of the thoracic aorta preparation of SHRSP by acetylcholine was much less (ca 38%) than that of WKY; however, that of SHRSP by glyceryltrinitrate was slightly less (ca 74%), indicating that endothelium-dependent relaxation declined in vascular preparation of SHRSP.4. The present results suggest that endothelium-dependent relaxation has some contribution on blood pressure regulation in the hypertensive state, although a decline of endothelium-dependent relaxation is evident in vascular preparation of SHRSP compared with WKY.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1991.tb01632.x
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  • 4
    Electronic Resource
    Electronic Resource
    SPECTROPHOTOMETRIC STUDY OF α-ADRENOCEPTORS AFFECTING MICROCIRCULATION OF RAT SKIN (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 α-adrenergic receptor subtypes that affect the microcirculation of skin, the relative absorption (RA) spectra of the skin on the backs of rats were measured using reflectance spectrophotometric methods. We injected α-adrenergic agonists, noradrenaline (NA), phenylephrine (PE) and clonidine (CL), intravenously and determined changes in the RA value at 569 nm, one of the isosbestic points of the oxyhaemoglobin and deoxyhaemoglobin absorption.2. NA reduced the RA value and the reduction was inhibited significantly by pretreatment with phenoxybenzamine (PBZ; P〈0.01). These findings suggested that the haemoglobin content in the skin tissue decreased as a result of vasoconstriction through α-adrenoceptors.3. NA, PE and CL produced dose-dependent reductions in RA. CL and NA produced virtually equipotent reductions except at the highest dose used. PE produced smaller effects. The potency of these drugs in terms of changes in RA did not correlate with their potency in terms of rises in systemic blood pressure (NA ≤ PE ≥ CL).4. Yohimbine (YO) inhibited the NA-induced reduction in RA to a greater degree than bunazosin (BU). Midaglizole, a specific α2-adrenergic antagonist, significantly and dose dependently inhibited the NA-induced reduction in RA.5. Although BU inhibited NA-induced reduction in RA only slightly, the effect was significant (P〈0.05). BU significantly inhibited PE-induced reduction (P〈0.01), but did not inhibit CL-induced reduction.6. These observations suggest that the microcirculation of the skin of the rat is affected mainly by α2-adrenoceptor mediated vasoconstriction. However, α1-adrenoceptor mediated vasoconstriction also has some effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1993.tb01719.x
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  • 5
    Electronic Resource
    Electronic Resource
    Skin mast cell promotion of matrix remodeling in burn wound healing in mice: relevance of chymase (1998)
    Springer
    Archives of dermatological research 290 (1998), S. 553-560 
    Details
    ISSN: 1432-069X
    Keywords: Key words Mouse burn model ; Capillary formation ; Collagen accumulation ; Chymase ; Skin mast cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Inflammation, granulation, and collagen accumulation, which are observed in the wound healing process, occasionally lead to hypertrophic scarring. Several in vitro reports have suggested that skin mast cells (MCs) and their major protease, chymase, participate in the healing process as well as in fibrotic skin diseases. The present study examined the potential involvement of MCs and MC chymase in the healing of burns in mouse dorsal skin. The size of the burn wounds, density of the capillaries, collagen accumulation, MC number, and chymase activity were measured before and 1, 3, 7, and 14 days after burning. The healing process corresponded strongly with MC density and chymase activity in both acute and subacute phases. The maximum decrease in MC number and chymase activity occurred on day 3 when tissue loss due to necrosis was maximal. From day 7 to 14, the burn wounds retracted rapidly accompanied by increases in capillaries and collagen fibers, in correspondence with fast increments in MC numbers and chymase activity at the wound edges. The present results combined with previous in vitro results strongly support the contention that skin MC chymase plays a role in the normal wound healing process, and presumably in dermal fibrotic disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050351
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