Myograph

A myograph is any device used to measure the force produced by a muscle when under contraction.[1] Such a device is commonly used in myography, the study of the velocity and intensity of muscular contraction.[2]

A myograph recording from a pendulum myograph after an induced contraction. The upper line (m) represents the curve traced by the end of the myograph lever in connection with a muscle after stimulation of the muscle by a single induction-shock.

A myograph can take several forms: for tubular structures such as blood vessels these include the pressure myograph (where a segment of a blood vessel is cannulated at either or both ends) and the wire myograph (where the blood vessel segment is threaded onto a pair of pins or wires); for skeletal muscle other devices such as the acceleromyograph can be used.

In pharmacology, myography is used to record muscle contraction in organ bath preparations. The related technique of electromyography (EMG) is used to measure the electrical activity of the muscle instead of force. In addition, there is an optomyography (OMG) technique that uses active near-infra-red optical sensors.

Wire Myograph

A wire myograph is a type of laboratory apparatus that can measure the contractility of luminal tissue segments smaller than 2mm in diameter.[3][4] It is used by pharmacologists to measure the effect of test articles on blood pressure or airway contractility.[5]

History of the wire myograph

Diagrams of the first ever wire myograph were revealed by Mulvany & Halpern in their 1976 paper "Contractile properties of small arterial resistance vessels in [...] rats".[6] The group based the design of this apparatus on a technique developed by Bevan & Osher to measure arterial contractility ex vivo.[7] Development of the wire myograph was significant as it allowed researchers to more accurately estimate the effect of novel drugs on blood pressure for the first time.[5][6]

Structure of the wire myograph

The structure of the wire myograph has not changed much since its invention in 1977. Tissues are mounted in the myograph bath via two wires threaded through their lumen.[3] These wires are attached to two opposing stainless steel jaws which secure tissue in place throughout the culture period.[3] Multi-myograph units can contain up to four separate tissue baths, allowing four different tissue segments to be cultured simultaneously.

References
  1. Blood, Douglas C.; Studdert, Virginia P. (Jan 15, 1999). Saunders Comprehensive Veterinary Dictionary. Saunders Ltd. ISBN 978-0-7020-2788-8.
  2. Urdang, Laurence (1981). -Ologies &- Isms: A Thematic Dictionary (2 ed.). Gale Research Co. ISBN 978-0-8103-1055-1.
  3. Spiers, Angela; Padmanabhan, Neal (2005), Fennell, Jérôme P.; Baker, Andrew H. (eds.), "A Guide to Wire Myography", Hypertension: Methods and Protocols, Totowa, NJ: Humana Press, pp. 91–104, doi:10.1385/1-59259-850-1:091, ISBN 978-1-59259-850-2, retrieved 2023-04-25
  4. Olson, K. R. (2011-01-01), Farrell, Anthony P. (ed.), "DESIGN AND PHYSIOLOGY OF ARTERIES AND VEINS | Physiology of Capacitance Vessels", Encyclopedia of Fish Physiology, San Diego: Academic Press, pp. 1111–1118, ISBN 978-0-08-092323-9, retrieved 2023-04-25
  5. "The ultimate guide to wire myography [Protocol Included]". www.reprocell.com. Retrieved 2023-04-25.
  6. Mulvany, M J; Halpern, W (July 1977). "Contractile properties of small arterial resistance vessels in spontaneously hypertensive and normotensive rats". Circulation Research. 41 (1): 19–26. doi:10.1161/01.RES.41.1.19. ISSN 0009-7330.
  7. Bevan, J. A.; Osher, J. V. (1972). "A direct method for recording tension changes in the wall of small blood vessels in vitro". Agents and Actions. 2 (5): 257–260. doi:10.1007/BF02087051. ISSN 0065-4299. PMID 4641160.
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