Characteristics of the myogenic behaviour of arteries of the common European frog ( Rana temporaria )

Comerford, L. and Bolger, N.M. and Bund, S.J. (2008) Characteristics of the myogenic behaviour of arteries of the common European frog ( Rana temporaria ). Acta Physiologica Hungarica, 95 (1). pp. 45-53. ISSN 0231-424X

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Abstract

Mammalian small arteries exhibit pressure-dependent myogenic behaviour characterised by an active constriction in response to an increased transmural pressure or an active dilatation in response to a decreased transmural pressure. This study aimed to determine whether pressure-dependent myogenic responses are a functional feature of amphibian arteries.Mesenteric and skeletal muscle arteries from the common European frog ( Rana temporaria ) were cannulated at either end with two fine glass micropipettes in the chamber of an arteriograph. Arterial pressure-diameter relationships (5–40 mmHg) were determined in the presence and absence of Ca2+ . All arteries dilated passively with increasing pressure in the absence of Ca2+ . In the presence of Ca2+ proximal mesenteric branches and tibial artery branches dilated with increasing transmural pressure but tone (p<0.05) was evident in both arteries. A clear myogenic response to a step increase or decrease in pressure was observed in small distal arteries (6 of 13 mesenteric and 7 of 10 sciatic branches) resulting in significantly (p<0.05) narrower diameters in Ca2+ in the range 10–40 mmHg in mesenteric and 20–40 mmHg in sciatic arteries, respectively.The results demonstrate that arteries of an amphibian can generate spontaneous pressure-dependent tone. This is the first study to demonstrate myogenic contractile behaviour in arteries of nonmammalian origin.

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