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First published online May 1, 2006
Journal of Experimental Biology 209, 1956-1963 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02228
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The role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles

Gina L. J. Galli1,2,3,*, Hans Gesser1, Edwin W. Taylor2, Holly A. Shiels3 and Tobias Wang1

1 Department of Zoophysiology, Aarhus University, Building 131, 8000 Aarhus C, Denmark
2 School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, B19 2TT, UK
3 Faculty of Life Sciences, The University of Manchester, 48 Grafton Street, Manchester, M13 9NT, UK


Figure 1
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  		Fig. 1. Force-frequency relationships and resting tension after treatment with different drugs (see key) in ventricular (A–D) and atrial (E–H) muscle from each species. (A,E) Turtle, Trachemys scripta (N=7); (B,F) python, Python regius (N=7); (C,G) tegu lizard, Tupinambis merianae (N=6); (D,H) varanid lizard, Varanus exanthematicus (N=8). The resting tension data is for untreated tissue only. Horizontal hatched grey bars indicate the species range of in vivo heart rate for each species. The last point on each curve displays an x-error, as the N-value is less than that stated above. Values are mean ± s.e.m. *Twitch force is significantly reduced following pre-treatment with ryanodine, {dagger}twitch force is significantly increased following treatment with adrenaline, and {ddagger}the frequency at which resting tension significantly increased (P<0.05).

 

Figure 2
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  		Fig. 2. Original traces from post-rest experiments. Representative trace of a 1 min (A) and 5 min (B) pause in ventricular muscle from a varanid lizard, Varanus exanthematicus. Stimulation ceased for a period of 1 min (A) and 5 min (B), and the following 5 contractions were recorded.

 

Figure 3
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  		Fig. 3. Representative trace of a 1 min pause in atrial tissue from a turtle, Trachemys scripta. Stimulation ceased for a period of 1 min, and the following 5 contractions were recorded.

 




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