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排序方式: 共有274条查询结果,搜索用时 15 毫秒
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Subtypes of alpha 1-adrenoceptors in rat blood vessels 总被引:13,自引:0,他引:13
Two alpha 1-adrenoceptor subtypes (alpha 1A and alpha 1B) have been distinguished by competitive antagonists and the alkylating agent chloroethylclonidine. The chloroethylclonidine-insensitive subtype (alpha 1A) has been suggested to selectively activate Ca2+ influx through dihydropyridine-sensitive channels in smooth muscle. We compared the effects of chloroethylclonidine and nifedipine on contractile responses to norepinephrine (NE) in rat blood vessels. Pretreatment with chloroethylclonidine caused a large shift to the right and decrease in maximum for NE-induced contractions of rat aorta, however, nifedipine had no effect in this tissue. Chloroethylclonidine had no effect on NE-induced contractions of rat renal arteries, which were almost completely abolished by nifedipine. Both chloroethylclonidine and nifedipine partially attenuated NE-induced contractions in rat mesenteric artery and portal vein. Addition of nifedipine abolished residual contractions remaining after chloroethylclonidine pretreatment in all four types of vessels. The pA2 for the competitive antagonist WB 4101 was highest in renal artery and lowest in aorta. These results suggest that the sensitivity of rat blood vessels to chloroethylclonidine is inversely related to their sensitivity to nifedipine, and support the existence of two alpha 1-adrenoceptor subtypes in rat blood vessels. Rat aorta appears to contain primarily alpha 1B receptors, renal artery primarily alpha 1A, and mesenteric artery and portal vein mixtures alpha 1A of and alpha 1B. 相似文献
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Ignatius KP CHENG 《Nephrology (Carlton, Vic.)》1997,3(1):109-111
Summary: The involvement of the IgA immune system and complement components in IgA glomerulonephritis (IgAGN) has prompted the use of immunosuppressive drugs in therapy, but none has so far been shown to alter the natural course of the disease. Because most patients with IgAGN present during the chronic phase of their illness, at the time when the initiating immune events may no longer be active, nonimmune therapy which targets the common pathway of progressive renal injury is likely to be more useful. There is increasing evidence that angiotensin-converting enzyme inhibitors (ACEI) reduce proteinuria and renal injury in patients with IgAGN, and this effect may be observed in both normotensive and hypertensive patients. Yet to be determined is whether this effect is specific for ACEI and whatever other effective antihypertensive drugs may achieve a similar result. Fish oil has recently been shown to retard the progression of renal failure in patients with aggressive IgAGN, but a narrow therapeutic window appears to exist for this form of treatment. Antiplatelet agents on their own appear to be ineffective but in combination with anticoagulation (low dose warfarin) have been shown to have an antiproteinuric effect and may preserve renal function in patients with progressive disease. Future directions of non-immune therapy of IgAGN include evaluation of the renoprotective effect of angiotensin II receptor antagonists, free-radical scavengers and antilipid drugs. More work should also be done to identify factors which put the patients at risk of developing progressive disease and which predict therapeutic response, as has been done recently with the identification of the deletion polymorphism of the angiotensin-converting enzyme gene as a marker of progressive disease and therapeutic response to ACEI in patients with IgAGN. 相似文献
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Myosin VIIA gene: heterogeneity of the mutations responsible for Usher syndrome type IB 总被引:8,自引:1,他引:8
Levy G; Levi-Acobas F; Blanchard S; Gerber S; Larget-Piet D; Chenal V; Liu XZ; Newton V; Steel KP; Brown SD; Munnich A; Kaplan J; Petit C; Weil D 《Human molecular genetics》1997,6(1):111-116
Usher syndrome is recognized as the most frequent cause of hereditary
deaf-blindness. Usher syndrome type I (USH1), the most severe form of the
disease, is characterized by profound congenital sensorineural deafness,
constant vestibular dysfunction, and retinitis pigmentosa of prepubertal
onset. This form is genetically heterogeneous and five loci (USH1A-E) have
been mapped thusfar. However, only the gene responsible for USH1 B (which
accounts for approximately 75% of USH1 cases) has been characterized. It
encodes a long-tailed unconventional myosin, myosin VIIA, with a predicted
2215 amino acid sequence. Primers covering the complete myosin VIIA coding
sequence as well as the 3' non coding sequence were designed, allowing
direct sequence analysis of each of the 48 coding exons and flanking splice
sites in seven patients affected by USH1. Four novel mutations were thereby
identified. The possibility should now be considered of a sequence-based
prenatal diagnosis in some of the families affected by this very severe
form of Usher syndrome.
相似文献
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Eric N. Juberg Kenneth P. Minneman Peter W. Abel 《Naunyn-Schmiedeberg's archives of pharmacology》1985,330(3):193-202
Summary The properties of
1- and
2-adrenoceptors in right and left atria of rat heart, and their roles in mediating chronotropic and inotropic responses to-adrenoceptor agonists were examined. [125I](-)-pindolol (125IPIN) bound saturably and specifically to a single class of high affinity sites in homogenates of both right and left atria. Thek
1's for association in right and left atria were 6.5×109 l/mol-min and 2.3×109 l/mol-min respectively, while thek
–1's for dissociation were 0.20 min–1 and 0.17 min–1. The kinetically determinedK
D's were 75 pmol/l in right and 30 pmol/l in left atria and were similar to the equilibriumK
D's determined from Scatchard analysis of saturation isotherms of specific125IPIN binding. Inhibition of125IPIN binding by-adrenoceptor antagonists was stereoselective and the order of potency was timolol > 1-propranolol > d-propranolol > sotalol. Inhibition by
1- and
2-adrenoceptor subtype selective antagonists yielded flat displacement curves with low Hill coefficients. Nonlinear regression analysis of displacement by
1-selective (practolol, atenolol and metoprolol) and
2-selective (ICI 118,551) antagonists gave estimates of the proportion of
1- and
2-adrenoceptors present in rat atria. Right atria contained 67±4.2%
2-adrenoceptors and 33±4.2%
2-adrenoceptor, while left atria contained 67±2.8%
1- and 33±2.8%
2-adrenoceptors. Increases in the rate of spontaneously beating right atria and the force of electrically driven left atria caused by-adrenoceptor agonists were also measured. pA2 values for non-subtype selective-adrenoceptor antagonists in inhibiting isoprenaline-induced increases in rate and force were highly correlated withK
D values determined for specific125IPIN binding. pA2 values for
1- and
2-selective antagonists in inhibiting isoprenaline-induced increases in rate and force correlated well with the pK
D values of these drugs in binding to
1-adrenoceptors, but not with the pK
D values in binding to
2-adrenoceptors. Dose-response curves for stimulation of both rate and force by the
2-selective agonists procaterol and zinterol were shifted to a much greater extent by selective blockade of
1-adrenoceptors with metoprolol than by selective blockade of
2-adrenoceptors with ICI 118,551, suggesting that these compounds caused their effects by activating
1-adrenoceptors. These results suggest that
1- and
2-adrenoceptors coexist in both left and right atria of rat heart in approximately a 21 ratio, however only
1-adrenoceptors mediate the chronotropic and inotropic effects of-adrenoceptor agonists.Supported by a grant from the American Heart Association — Georgia Affiliate 相似文献
8.
Aneurysm of sinus of Valsalva dissecting into interventricular septum is a rare entity. We report one such case who was incidentally diagnosed by echocardiography to have this abnormality during evaluation of a clinically suspected isolated aortic regurgitation.KEY WORDS: Aneurysm – dissecting – sinus of Valsalva, Echocardiography 相似文献
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