The priming principle revisited.
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Humans↗
Biomedical subjects
S D Gergis
Publications and source records attributed to S D Gergis.
Malignant hyperthermia.
A short review of the history, incidence, and present-day concept of the etiology of malignant hyperthermia is presented. Protocols for diagnosis, treatment of the unexpected occurrence, and management of known malignant hyperthermic patients is presented. The exact etiology of the syndrome is still unknown.
Anesthesia, Inhalation↗
Outpatient anesthesia.
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Ambulatory Care↗
Effect of sodium nitroprusside and trimetaphan on neuromuscular transmission in the frog.
In summary, it appears from this and other studies that trimetaphan has the potential for producing neuromuscular blockade when used in large doses or when combined with other muscle relaxants. The mode of action appears to be principally that of non-depolarizing neuromuscular blockade. Sodium nitroprusside, on the other hand, even in doses beyond these accepted clinically, does not affect neuromuscular transmission and unless otherwise contraindicated is safe to use with muscle relaxants.
Acetylcholine↗
Studies of the neuromuscular blocking effects of BW 403C65 in frog and cat muscle.
BW 403C65, an isoquinolinium bisquaternary compound, was investigated for its neuromuscular blocking properties. In vitro in from preparations, low concentrations induced an increase in miniature endplate potentials (m.e.p.p.) frequency without altering their amplitude. With increasing concentrations m.e.p.p. frequency returned to control value and amplitude started to decrease concomitantly with the decreased sensitivity of the endplate to iontophoretically applied acetylcholine and depression of the twitch tension. Acetylcholine released at the neuromuscular junction was also decreased. In vivo in the cat preparation the intra-arterial injection of low doses of the drug produced an increase in the strength of the muscle twitch, and the development of contracture, as well as the appearance of post-drug repetition at the ventral roots. Greater doses produced a progressive decline in post-tetanic potentiation with prolonged return to control.
Acetylcholine↗
Actions of a new muscle relaxant (AH8165) on neuromuscular transmission.
The effects of a new muscle relaxant, AH8165, on miniature endplate potential (MEPP) amplitude and frequency, endplate sensitivity to acetylcholine, and muscle twitch tension were studied in vitro in the frog sartorius muscle. Nerve terminal effects were studied in vivo in the cat soleus muscle and its ventral root fibers. AH8165 stimulates the nerve terminal, as evidenced by increased MEPP frequency and the appearance of post-drug repetitive activity. In the same concentration range at which MEPP frequency is increased, MEPP amplitude, endplate sensitivity to acetylcholine, and twitch tension are decreased. This suggests that AH8165 produces muscle relaxation by blocking postsynaptic cholinergic receptors. (Key works: Neuromuscular relaxants, AH8165.).
Acetylcholine↗
Comparative neuromuscular effects of lincomycin and clindamycin.
The effects of lincomycin and clindamycin on neuromuscular transmission in vitro were studied. Standard microelectrode technics were used to measure miniature endplate potential (MEPP) amplitude and frequency, and endplate sensitivity to acetycholine on the frog sartorius muscle. Twitch tension and nerve terminal acetycholine release were also studied. In the drug concentration range where twitch tension changes occurred, both drugs caused marked decreases in MEPP amplitude and decreases in endplate sensitivity to iontophoretically applied acetylcholine. Lincomycin did not alter MEPP frequency but decreased acetylcholine release. Clindamycin increased MEPP frequency and increased acetylcholine release. The study shows that both lincomycin and clindamycin cause blockade of neuromuscular transmission through a postsynaptic action. However, at high concentrations, lincomycin has a nerve-terminal depressant effect, while clindamycin has a marked presynaptic stimulatory effect.
Acetylcholine↗
Procaine, lidocaine, and ketamine inhibit histamine-induced contracture of guinea pig tracheal muscle in vitro.
In vitro experiments using guinea pig tracheal smooth muscle were performed to compare the relaxant properties of procaine, lidocaine, and ketamine following contracture induced by histamine. Procaine produced a spasmolytic effect in a dose-related manner. In the doses tested, relaxation induced by procaine was more pronounced than that produced by either lidocaine or ketamine, although the latter 2 drugs also had a significant spasmolytic effect.
Anesthesia, Local↗
Management of suspected malignant hyperpyrexia in an infant.
A case of possible malignant hyperthermia in a 6-month-old child is presented. Malignant hyperthermia was manifested in this patient by persistent metabolic acidosis in the intraoperative and postoperative periods, by a rapid rise in temperature with concomitant unresponsiveness in the postoperative period, and by a positive caffeine-halothane stimulation test. The malignant hyperthermia occurring in the postoperative period resolved promptly following administration of dantrolene sodium. An unusual aspect of this case is that both of the child's parents had normal CPK values and negative caffeine-halothane stimulation tests.
Caffeine↗