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Gillespie JS, McGrath JC.
“The Response of The Cat inococaygeus Muscle to Nerve or Drug Stimulation and a Comparison with the Rat Anococcygeus.”.
Brit.J.Pharmacol.. 1974;50(1):109-18.
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Abstract
The responses of the cat and rat anococcygeus muscle to nerve and drug stimulation were compared. Methods Comparisons were made in rat and cat anococcygeus muscles isolated in Kreb's solution, isometric tension being recorded. Noradrenaline (Koch-Light) (10 5M), adrenaline (Koch-Light) and 5-HT (Koch-Light) all caused contraction in the cat muscle, the first 2 being equipotent and antagonized by phentolamine (CIBA) (10 6M) and potentiated by propranolol (Sigma) (10 EM). Contractions to 5-HT were antagonized by methysergide (Sandoz) (2 x 10 7 M) Rat muscle showed similar responses, but was 100 times more sensitive to 5-HT. Tyramine (Sigma) (3 x 10 7 M), amphetamine (3 x 10 M), cocaine (10 5M), guanethidine (CIBA) (10 6M) and LSD (Sandoz) (10 aM) all caused contraction in both cat and rat muscle preparations. In the rat no drug capable of causing inhibition was found. In the cat acetylcholine (Koch - Light), carbachol (Wellcome), iso-prenaline (Sigma), ATP (Sigma), prostaglandins El, Ez and F2 and vasopressin (Parke-Davis), all motor in the rat, all caused inhibition, especially if the tone of the preparation was first raised by the addition of 5-HT, tyramine or guanethidine. The inhibitory effects of acetylcholine and carbachol were both abolished by atropine, and that of isoprenaline by propranolol. Field stimulation of the rat muscle caused a motor response, depressed then reversed by increasing dosage of guanethidine. The cat muscle was similar. Phentolamine (CIBA), atropine, hexamethonium (Koch-Light), pancuronium (Organon), mepyramine (May+Baker) and propranolol did not alter the inhibitory response of cat muscle to any stimulus, and only phentolamine blocked the motor response. Neostigmine (Roche) did not effect inhibitory or motor responses of cat muscle to field stimulation at any frequency, but it did potentiate the motor response to acetylcholine in the rat muscle, and the inhibitory response to this agent in cat mus cle. Cold storage for up to 8 days had little effect upon either the motor response to noradrenaline or- motor or inhibitory responses to field stimulation in cat muscle. With longer storage the res-ponse to field stimulation diminished more rapidly than that to noradrenaline, and histochemical examination showed loss of noradrenaline fluorescence Conclusion Cat anococcygeus muscle has dual innervation similar to that of the rat, with a motor adrenergic innervation and an inhibitor innervation with an unknown transmitter.
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