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At least 991 records · Page 55Linked to original sources
PubMed2000

Do muscle relaxants influence vascular tone in isolated coronary artery segments?

The aim of this study was to elucidate the influence of four neuromuscular blocking substances on coronary vascular tone using the model of isolated porcine coronary artery segments. We studied the effects of four muscle relaxants, atracurium, pancuronium, rocuronium, and vecuronium (0.1, 1, and 10 microg mL-1 each), on the contractile response to three vasoconstrictors: acetylcholine, histamine, and serotonin. None of the neuromuscular blocking agents under investigation exerted a significant influence on the vasoconstricting effects of these mediators except for pancuronium, which dose-dependently attenuated acetylcholine-mediated contractions (-10.8% attenuation for 10 microg mL-1 pancuronium, P < 0.05). There was no difference between vessels with intact endothelium and denuded preparations. It is concluded that high-dose pancuronium exerts an antimuscarinic effect in vascular smooth muscle. The other neuromuscular agents studied do not alter vascular reactivity of isolated porcine coronary arteries.

Acetylcholine↗
PubMed1995

Muscle relaxants and histamine release.

Many anaesthetic drugs and adjuvants can cause the release of histamine by chemical (anaphylactoid) or immunologic (anaphylactic) mechanisms. While both types of reactions can be clinically indistinguishable, they are mechanistically different. In anaphylactoid reactions, only preformed mediators are released, of which histamine may be the most clinically important. In true immunologic reactions, mast cell degranulation occurs, and many vasoactive substances (including histamine) are released. Clinical signs and symptoms of both classes of reactions include hypotension (most common), tachycardia, bronchospasm, or cutaneous manifestations. Anaphylactoid reactions may occur commonly under anaesthesia in response to many drugs, including induction agents, some opiates, plasma expanders, and curariform relaxants. Anaphylactic reactions are far less common than anaphylactoid reactions, but they nevertheless represent more than half of the life-threatening reactions that occur in anaesthetic practice. Muscle relaxants are the most frequently implicated class of drugs; suxamethonium is the most common agent implicated in anaphylactic reactions during anaesthesia, but even drugs without apparent chemical histamine release (i.e., vecuronium) are frequently implicated in anaphylactic reactions.

Anaphylaxis↗
PubMed1997

[Effects of melatonin on muscle contractility and neuromuscular blockade produced by muscle relaxants].

Effects of melatonin on muscle contractility and on the blocking properties of succinylcholine and vecuronium were investigated in vitro using phrenic nerve-hemidiaphragm preparations of rats. Melatonin (26-520 microM) alone had almost no effect on the contractility. Melatonin (260 microM) markedly potentiated the block produced by succinylcholine, but melatonin had no effect on the block produced by vecuronium. Because the property of the block produced by succinylcholine is nicotinic receptor desensitization, we consider that melatonin potentiates succinylcholine-induced block with facilitation of the desensitization. These results suggest that melatonin has calcium channel blocking effect.

Animals↗
PubMed1990

Smooth muscle relaxing flavonoids from Alchornea cordifolia.

Alchornea cordifolia (Schum. & Thonn.) Muell. Arg. (Euphobiaceae) is widely distributed throughout tropical Africa, where it is used extensively in traditional medicine. Conditions for which the plant has enjoyed wide use are: coughs, gonorrhoea, yaws, ulcer, rheumatic pains, fever and bronchial troubles. This paper reports isolation of smooth muscle relaxing flavonoids from the leaves of the plant.

Africa↗
PubMed1995

Study of clinical anaesthesia with pedius A anaesthesia system using ketamine or halothane with muscle relaxant.

In pedius anaesthesia system, oxygen enriched air and air are generated through an electrically driven oxygen generator 'Permox', obviating the need of compressed gas cylinder or pipe line. Effect of anaesthesia with pedius A anaesthesia system using ketamine or halothane with muscle relaxant in 2 groups of patients had been studied. Both groups had satisfactory results clinically. It appears that if the cases are carefully selected, both the agents have got equal effectiveness.

Adult↗
PubMed2005

New insights into beta-adrenoceptors in smooth muscle: distribution of receptor subtypes and molecular mechanisms triggering muscle relaxation.

1. The beta-adrenoceptor is currently classified into beta(1), beta(2) and beta(3) subtypes and all three subtypes are expressed in smooth muscle. Each beta-adrenoceptor subtype exhibits tissue-specific distribution patterns, which may be a determinant controlling the mechanical functions of corresponding smooth muscle. Airway and uterine smooth muscles abundantly express the beta(2)-adrenoceptor, the physiological significance of which is established as a fundamental regulator of the mechanical activities of these muscles. Recent pharmacomechanical and molecular approaches have revealed roles for the beta(3)-adrenoceptor in the gastrointestinal tract and urinary bladder smooth muscle. 2. The beta-adrenoceptor is a G(s)-protein-coupled receptor and its activation elevates smooth muscle cAMP. A substantial role for a cAMP-dependent mechanism(s) is generally believed to be the key trigger for eliciting beta-adrenoceptor-mediated relaxation of smooth muscle. Downstream effectors activated via a cAMP-dependent mechanism(s) include plasma membrane K(+) channels, such as the large-conductance, Ca(2+)-activated K(+) (MaxiK) channel. 3. Beta-Adrenoceptor-mediated relaxant mechanisms also include cAMP-independent signalling pathways. This view is supported by numerous pharmacological and electrophysiological lines of evidence. In airway smooth muscle, direct activation of the MaxiK channel by G(s)alpha is a mechanism by which stimulation of beta(2)-adrenoceptors elicits muscle relaxation independently of the elevation of cAMP. 4. The cAMP-independent mechanism(s) is also substantial in beta(3)-adrenoceptor-mediated relaxation of gastrointestinal tract smooth muscle. However, in the case of the beta(3)-adrenoceptor, a delayed rectified K(+) channel rather than the MaxiK channel seems to mediate, in part, cAMP-independent relaxant mechanisms. 5. In the present article, we review the distribution of beta-adrenoceptor subtypes in smooth muscle tissues and discuss the molecular mechanisms by which each subtype elicits muscle relaxation, focusing on the roles of cAMP and plasma membrane K(+) channels.

Adrenergic Agonists↗