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The Effect of Curare on Muscle Tension

Used for centuries by aboriginal hunters of South America to immobilize their prey and, more recently, by modern medicine as a muscle relaxant, the active ingredient in curare destroys muscle tension, rendering muscles useless.

  1. Muscle Tension

    • Muscle tension depends on the capacity of muscle fibers to contract, which in turn depends on incoming nerve impulses reaching muscle fibers, according to the book "Human Physiology."

    Blocking Effect

    • Curare's key active ingredient, tubocurarine, prevents motor-nerve impulses from reaching muscle fibers, observes Richard A. Lehne, Ph.D., formerly of the pharmacology department at the University of Virginia School of Medicine.

    Paralysis

    • The presence of curare in the spaces between motor nerves and muscle fibers makes muscle tension impossible, resulting in paralysis.

    Time Line

    • Tubocurarine first paralyzes the muscles of the eyelid and chewing (mastication), then of the limbs, abdomen and voice box (glottis) and finally of respiration, possibly killing the drugged victim by respiratory arrest, according to Lehne.

    Context

    • The loss of muscle tension comes along with a drop in blood pressure, due to tubocurarine's triggering the release of histamine, but since the drug leaves the central nervous system untouched, the affected person remains susceptible to pain and perfectly conscious even when totally paralyzed, according to the book "Pharmacology for Nursing Care."

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