Vasopressors norepinephrine noradrenaline

Purslane contains large amounts of /-norepinephrine (/-noradrenaline 0.25% in fresh herb), a neurohormone that has vasopressor and antihypotensive activities and reduces hemorrhage at the tissue level (jiangsu martindale). 

Norepinephrine is the primary neurotransmitter produced and released by adrenergic neurons, and in literature it is also described as and called (-) noradrenaline or levarterenol. This vasopressor catecholamine reduces both the resistance and capacity of blood vessels by stimulating a-adrenoreceptors and having a direct cardiostimulatory effect, which is accomplished by activation of )3i-adrenoreceptors. Norepinephrine exhibits significantly less activity than epinephrine as a drug for widening blood vessels through the activation of jSj-adrenoreceptors. Elevation of both stylistic and diastolic blood pressure is a typical reaction to intravenous introduction of norepinephrine. 

An interaction is established, although the exact outcome of the concurrent use of clonidine and these sympathomimetic vasopressors is not clear. It has been suggested that the effects may be different at different doses of dopamine. The authors of the one report, studying phenylephrine and noradrenaline (norepinephrine) with clonidine, suggested that the increase in pressor response was unlikely to be clinically significant. 

These are established interactions, but the paucity of clinical information suggests that in practice they do not present many problems, perhaps because the effects of these vasopressors are so closely monitored, and titrated to effect. If a pressor drug is required, a directly-acting drug such as noradrenaline (norepinephrine) or phenylephrine may be expected to be effective. The receptors may show some supersensitivity so that a dosage... 

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