Effect of Transmembrane pH Gradient Changes on Potassium-Induced Relaxation in Vascular Smooth Muscle

Karaki, Hideaki; Weiss, George B.

doi:10.1159/000158336

Cited by 10 publications

(9 citation statements)

References 18 publications

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“…However, ouabain, which inhibited K+-induced relaxation in the taenia coli, was ineffective in rat duodenum ( Figure 5). This may be due to insensitivity of the Na+/K+-ATPase of the rat duodenum to ouabain, since resistance of the enzyme to inhibition by this glycoside in other rat tissues has been demonstrated (Allen & Schwartz, 1969;Webb & Bohr, 1978;Karaki & Weiss, 1981).…”

Section: Discussionmentioning

confidence: 99%

Further evidence for the existence of two receptor sites for bradykinin responsible for the diphasic effect in the rat isolated duodenum

Boschcov

Paiva

et al. 1984

British J Pharmacology

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1 Low doses of bradykinin (below 10 nM), as well as of K+ (below 10 mM) induced relaxation, whereas higher doses caused contraction of the rat duodenum. 2 The relaxant responses induced by bradykinin and K+ were not affected by ouabain (1 LLM), but pre-incubation with 5.9 mM K+ abolished the responses to that ion but not those to bradykinin.3 The contractile and relaxant components of the response to bradykinin (but not those to K+) increased with the time elapsed after mounting of the preparation, and this was due to stretching by the load of the recording system. 4 Specific and reversible desensitization (tachyphylaxis) was observed with the contractile response (but not the relaxation) induced by bradykinin. 5 Des-Arg9-bradykinin, an analogue specific for B1-receptors, was much less active than bradykinin, and elicited only a contractile response. 6 Among four bradykinin potentiating peptides that were tested, potentiator C enhanced the relaxation only, whereas BPP5a and captopril potentiated only the contraction and BPP9a potentiated both types of response to bradykinin. 7 Our results support the hypothesis that the relaxant and contractile components of the rat duodenum's response to bradykinin are due to actions at different receptor sites, which can be distinguished by their properties (desensitization) and their different apparent affinities for agonists and for potentiating peptides.

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Section: Discussionmentioning

confidence: 99%

Further evidence for the existence of two receptor sites for bradykinin responsible for the diphasic effect in the rat isolated duodenum

Boschcov

Paiva

et al. 1984

British J Pharmacology

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“…In the presence of carbonic anhydrase, CO2 is quickly hydrated to form carbonic acid and its dissociation products, bicarbonate and hydrogen ions. The resultant acidic extracellular environment enhances the vasodilatory effect of adenosine (72) and increases potassium ion conductance across vascular smooth muscle (73), resulting in blood vessel dilation and thus increased flow (74). The effect of pH on cerebral vascular tone may be mediated by a variety of factors, including nitric oxide (NO) (75), lactate (76), prostanoids (77), cyclic nucleotides (78), potassium channels (79) and intracellular calcium (80).…”

Section: Mechanisms Of Effectmentioning

confidence: 99%

Anxiety, respiration, and cerebral blood flow: implications for functional brain imaging

Giardino

Friedman

Dager

2007

Comprehensive Psychiatry

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Brain functional imaging methods, such as fMRI, are sensitive to changes in cerebral blood flow (CBF) that are normally associated with changes in regional neural activation. However, other endogenous and exogenous factors can alter CBF independently of brain neural activity, thus complicating the interpretation of functional imaging data. The presence of an anxiety disorder, as well as change in state anxiety, is often accompanied by respiratory alterations that affect arterial CO 2 tensions and produce significant changes in CBF that are independent of task-related neural activation. Therefore, the effects of trait and state anxiety need to be given close consideration in interpreting functional imaging findings. In this paper, we review the dependence of most brain functional imaging methods on localized changes in CBF and the potentially confounding effects of anxiety-related alterations of respiration on interpreting patterns of functional activation. Approaches for addressing for these effects are discussed.

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“…1978;Turlapaty et al 1979;Altura et al 1980). However, other investigators d o not find these effects with Tris (Johansson et al 1979;Karaki & Weiss 1981b;Karaki et al 1981a & b). The present study is an attempt t o further elucidate the transient and sustained effects of shifts between bicarbonatephosphate (Krebs), Tris or HEPES buffered solutions, and the role of p H and the membrane potential in these responses.…”

mentioning

confidence: 69%

“…Such a change in pHo has been shown to activate smooth muscle contractile mechanism (Schadler 1967) and to increase pH, (Karaki & Weiss 1981a). Such a change in pHo has been shown to activate smooth muscle contractile mechanism (Schadler 1967) and to increase pH, (Karaki & Weiss 1981a).…”

Section: Discussionmentioning

confidence: 98%

“…In the present results a change in pHo by 0.2 p H units above control (7.4) caused about 25% increase in contractile activity. Such a change in pHo has been shown to activate smooth muscle contractile mechanism (Schadler 1967) and to increase pH, (Karaki & Weiss 1981a). A change in pH, has been shown to change the Ca-sensitivity of actomyosin ATP-ase (Mrwa et al 1974).…”

Section: Discussionmentioning

confidence: 99%

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Comparison of Portal Vein Responsiveness in Tris, HEPES or Bicarbonate‐Phosphate Buffered Media

Sigurdsson

1983

Acta Pharmacologica et Toxicologica

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The effects of using Tris or HEPES buffered solutions instead of bicarbonate-phosphate buffered solution on the spontaneous activity of the rat portal vein were studied. The effect of the solution buffered with Tris on the spontaneous contractile activity was a minor change in amplitude and frequency, increasing the integrated isometric force by about 20%. A small increase in the mechanical response to variations in [Ca2']o (1.0-2.5 mM) was also observed. The response to field stimulation of intramural nerves was significantly lowered in Tris but the response to exogenous noradrenaline was not affected. HEPES buffer does not significantly affect the spontaneous activity, the concentration-effect curve for Ca", the response to field stimulation or to exogenous noradrenaline. Transient changes in the spontaneous activity and the resting membrane potential were observed when the solution was changed from Krebs to Tris (or HEPES) solution or vice versa. These changes disappear if the Tris or HEPES solutions were aerated with 4% C02 in 0 2 (at pH 7.4) instead of pure 0 2 . A small change in extracellular pH (k0.2 pH units) significantly affects the spontaneous activity. A change in pH may be the reason for the observed effects in the different buffer media.

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Effect of Transmembrane pH Gradient Changes on Potassium-Induced Relaxation in Vascular Smooth Muscle

Cited by 10 publications

References 18 publications

Further evidence for the existence of two receptor sites for bradykinin responsible for the diphasic effect in the rat isolated duodenum

Further evidence for the existence of two receptor sites for bradykinin responsible for the diphasic effect in the rat isolated duodenum

Anxiety, respiration, and cerebral blood flow: implications for functional brain imaging

Comparison of Portal Vein Responsiveness in Tris, HEPES or Bicarbonate‐Phosphate Buffered Media

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