Mechanical properties of tracheal smooth muscle: effects of temperature.

The effect of temperature on the isometric tetanic myogram was studied in isolated canine tracheal smooth muscle (TSM). At 37 degrees C and 27 degrees C no significant change occurred in maximum tetanic tension (PO). At 17 degrees C a significant reduction was seen Values of Q10 for contraction time (tPO) were almost halved, whereas those for rate of tension development (dP/dt) were almost doubled. The effect of the same temperatures on the force-velocity (F-v) relationships was also studied. All three F-v curves were described by the Hill equation, (P + a) (v + b) = (PO + a)b. Vmax and b decreased with decreased temperature, with Q10's demonstrating they were dependent on active processes. Finally, the decreased dP/dt of the myogram at lower temperatures was felt to be the probable result of decreased contractile element velocity because no decrease in series elastic component stiffness was demonstrable, there being instead an increase in stiffness at lower temperatures.

[1]  J. Belehradek.  Physiological aspects of heat and cold. , 1957, Annual review of physiology.

[2]  R. A. Murphy,et al.  Force‐Velocity and Series Elastic Characteristics of Smooth Muscle from the Hog Carotid Artery , 1974, Circulation research.

[3]  R. Meiss.  Some mechanical properties of cat intestinal muscle. , 1971, The American journal of physiology.

[4]  K. Edman,et al.  The influence of temperature on the force-velocity relationship in rabbit papillary muscle. , 1974, Acta physiologica Scandinavica.

[5]  A. Csapo.  Dependence of isometric tension and isotonic shortening of uterine muscle on temperature and on strength of stimulation. , 1954, The American journal of physiology.

[6]  R. Close,et al.  Influence of Temperature on Isometric Contractions of Rat Skeletal Muscles , 1968, Nature.

[7]  W. Crozier,et al.  THE DISTRIBUTION OF TEMPERATURE CHARACTERISTICS FOR BIOLOGICAL PROCESSES; CRITICAL INCREMENTS FOR HEART RATES , 1926, The Journal of general physiology.

[8]  G. Langer,et al.  The Effects of Temperature upon Contraction and Ionic Exchange in Rabbit Ventricular Myocardium , 1968, The Journal of general physiology.

[9]  A. Huxley,et al.  Proposed Mechanism of Force Generation in Striated Muscle , 1971, Nature.

[10]  Active state of muscle and the second and third derivatives of twitch tension. , 1968, The American journal of physiology.

[11]  N. Stephens,et al.  Mechanical properties of tracheal smooth muscle and effects of O2, CO2, and pH. , 1970, The American journal of physiology.

[12]  N. Stephens,et al.  Force-velocity characteristics of respiratory airway smooth muscle. , 1969, Journal of applied physiology.

[13]  E. Sonnenblick,et al.  SERIES ELASTIC AND CONTRACTILE ELEMENTS IN HEART MUSCLE: CHANGES IN MUSCLE LENGTH. , 1964, The American journal of physiology.

[14]  A. Hill.  The heat of shortening and the dynamic constants of muscle , 1938 .

[15]  W. Parmley,et al.  Effects of temperature on series elasticity and contractile element motion in heart muscle. , 1969, The American journal of physiology.

[16]  R. Close.  Dynamic properties of mammalian skeletal muscles. , 1972, Physiological reviews.

[17]  M. Ehl,et al.  Force velocity relationships in vascular smooth muscle , 1975, Pflügers Archiv.