Weak β-adrenoceptor-mediated relaxation in the human internal mammary artery

He, Guo‐Wei; Buxton, Brian F.; Rosenfeldt, Franklin; Wilson, A.; Angus, James A.

doi:10.1016/s0022-5223(19)35333-4

Cited by 62 publications

(33 citation statements)

References 13 publications

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“…Resting vessel parameters [15,17,18] Seventy-eight rings taken from 22 patients were used in this study. The mean internal diameter of these rings at an equivalent transmural pressure of 100 mmHg (D100) was 1.99 ± 0.05 mm as determined from the normalization procedure.…”

Section: Resultsmentioning

confidence: 99%

“…were based on comparable resting tension which was determined by the individual length-tension curve of each IMA ring [15][16][17][18][19]. Unlike other studies on the human IMA [26,28], in the present study, we continuously measured the individual length-tension curve in the IMA rings.…”

Section: Discussionmentioning

confidence: 99%

“…The IMA was transferred into a glass dish and dissected out from its surrounding connective tissue. The IMA was then cut into 3 mm long rings, and the rings were then suspended on wires in organ baths [15][16][17][18][19]. The number of rings taken from each patient varied from 3-6.…”

Section: Generalmentioning

confidence: 99%

“…Relaxation oL-adrenoceptor agonists noradrenaline (NA, a1and a2-agonist) and methoxamine (MO, (x1agonist) were used to contract IMA rings to a stable level. The concentrations of NA and MO were submaximal concentrations which were determined from the logistic-curve fitting equation [15][16][17][18] from the previous work for NA (10 FLM) and for MO (30 FM) [17][18][19]. These concentrations are equal to EC50-EC80 for the NAor MO-induced contraction in the human IMA [16,18,19].…”

Section: Protocolmentioning

confidence: 99%

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Inhibitory effects of calcium antagonists on alpha‐adrenoceptor‐ mediated contraction in the human internal mammary artery.

Acuff

Ryan

et al. 1994

Brit J Clinical Pharma

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1. The internal mammary artery has become a preferred coronary bypass graft. Sympathomimetic amines are spasmogens for vasospasm and calcium antagonists are frequently administered drugs perioperatively. The effect of calcium antagonists on alpha‐adrenoceptor‐mediated contraction depends on the subtype of alpha‐adrenoceptor and the type of origin of vascular smooth muscle. This study was designed to investigate the effect of calcium antagonists on alpha‐adrenoceptor‐ mediated contraction in the IMA. 2. Human IMA segments taken from 22 patients undergoing IMA—coronary artery bypass grafting were mounted in an organ bath under the physiological pressure determined from their own length‐tension curves. 3. Three ring segments were allocated into three groups. One served as a control and the others were treated with clinically related concentrations of nifedipine (20 or 200 nM) for 25 min before concentration‐contraction curves to alpha 1‐adrenoceptor agonist methoxamine (MO) or full alpha‐adrenoceptor agonist noradrenaline (NA) were established. 4. In separate experiments, the concentration‐relaxation curves to nifedipine were established in the IMA rings precontracted with MO (30 microM) or NA (10 microM). Glyceryl trinitrate (GTN, 3 microM) was added to further relax the vessels. 5. Pretreatment with nifedipine (200 nM) only slightly inhibited the MO‐ (1.74 +/‐ 0.32 vs 2.88 +/‐ 0.56 g) or NA‐ (2.43 +/‐ 0.66 vs 3.60 +/‐ 0.82 g) induced contraction without statistical significance (P > 0.05). 6. On the other hand, nifedipine only caused 34.49% relaxation in the MO‐precontracted and 24.39% relaxation in the NA‐precontracted IMAs. In contrast, GTN caused 76.16% (against MO, P < 0.05) or 92.22% (against NA, P < 0.0001) relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Generalmentioning

confidence: 99%

Section: Protocolmentioning

confidence: 99%

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Inhibitory effects of calcium antagonists on alpha‐adrenoceptor‐ mediated contraction in the human internal mammary artery.

Acuff

Ryan

et al. 1994

Brit J Clinical Pharma

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“…A specially designed normalization technique was used in this study. Full details of this technique have been published previously (He et al, 1988(He et al, , 1989b. In brief, the IMA rings were stretched in progressive steps to determine the length-tension curve for each IMA ring.…”

Section: Organ-bath Techniquementioning

confidence: 99%

Inhibitory effects of glyceryl trinitrate on alpha‐adrenoceptor mediated contraction in the human internal mammary artery.

Shaw

Yang

et al. 1992

Brit J Clinical Pharma

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1. Sympathomimetic amines have been considered to be related to vasospasm. Previous studies showed that the human internal mammary artery (IMA) was capable of weak beta‐adrenoceptor mediated relaxation and that alpha‐adrenoceptor agonists may induce contraction in the human IMA. 2. We investigated the effects of glyceryl trinitrate (GTN), a vasodilator agent often used perioperatively, on alpha‐adrenoceptor mediated contraction in the human IMA. 3. Discarded human IMA segments were taken from 37 patients who underwent IMA‐coronary artery bypass graft operations and equilibrated in an organ bath. 4. A specially designed technique was used to normalize the vessel segments under the pressure similar to the in vivo situation. Noradrenaline (NA), phenylephrine (PE), and methoxamine (MO) were used to contract the vessel segments. 5. GTN fully relaxed PE or MO (submaximal concentration) induced precontraction. Therapeutic plasma concentration of GTN relaxed 40‐90% of the PE induced contraction (2.82 g, EC50 = 7.92 +/‐ 0.06 ‐log M) and 20‐90% of the MO induced contraction (1.8 g, EC50 = 7.63 +/‐ 0.16 ‐log M). Pretreatment by the therapeutic plasma concentration of GTN inhibited the contraction induced by NA, PE in a different range. It reduced the NA induced contraction (6.9 g) by 14.8‐ 38% (P greater than 0.05) and the PE induced contraction (4.3 g) by 7.9‐ 39.3% (P greater than 0.05). The alpha 1‐adrenoceptor antagonist prazosin, at the therapeutic plasma concentration, nearly totally abolished the NA or PE induced contraction (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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Vascular reactivity of arterial coronary artery bypass grafts—implications for their performance

Dzimiri

Chester

et al. 1996

Clinical Cardiology

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Summary: Specific properties of the vessel wall of arteries employed as coronary bypass grafts are thought to play an important role in the short-and long-term performance of these conduits. Heterogeneity in the endothelial and smooth muscle cell function between different arteries may provide particular vessels with properties which will favor them for use as bypass conduits. The aim of this review is to provide an insight into how the vascular reactivity of presently used arterial conduits varies and to discuss the clinical implications of these findings both in terms of flow modulation in response to physiologic and exogenous vasoactive mediators and longterm patency.

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Weak β-adrenoceptor-mediated relaxation in the human internal mammary artery

Cited by 62 publications

References 13 publications

Inhibitory effects of calcium antagonists on alpha‐adrenoceptor‐ mediated contraction in the human internal mammary artery.

Inhibitory effects of calcium antagonists on alpha‐adrenoceptor‐ mediated contraction in the human internal mammary artery.

Inhibitory effects of glyceryl trinitrate on alpha‐adrenoceptor mediated contraction in the human internal mammary artery.

Vascular reactivity of arterial coronary artery bypass grafts—implications for their performance

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