This Article Full Text Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jain, M. Articles by Morgan, K. G. Search for Related Content PubMed PubMed Citation Articles by Jain, M. Articles by Morgan, K. G.

(Circulation. 1996;94:1083-1088.)
© 1996 American Heart Association, Inc.

Articles

Intrinsic Tone as Potential Vascular Reserve in Conductance and Resistance Vessels

Mukesh Jain, MD; Hai Bin Dai, MD; Joseph P. Carrozza, MD; Frank W. Sellke, MD; Kathleen G. Morgan, PhD

the Cardiovascular Division, Department of Medicine (M.J., J.P.C., K.G.M.), and the Department of Cardiothoracic Surgery (H.B.D., F.W.S.), Beth Israel Hospital, and the Program in Smooth Muscle Research (M.J., K.G.M.), Harvard Medical School; and Boston Biomedical Research Institute (K.G.M.), Boston, Mass.

Correspondence to Mukesh K. Jain, MD, Cardiovascular Biology Laboratory, Harvard School of Public Health, Harvard Medical School, 677 Huntington Ave, Bldg 2, Rm 113A, Boston, MA 02115.

Background The purpose of this study was to define the degree of intrinsic tone in conductance and resistance vessels, to define the calcium dependency of intrinsic tone in these vascular preparations, and to investigate the efficacy of vasodilatory agents on the level of intrinsic tone in these vascular preparations.

Methods and Results All vessels were deendothelialized. Isometric force was recorded from strips of ferret aorta, ferret pulmonary artery, and human coronary artery. Vessel diameter was recorded from the ferret epicardial coronary artery and from ferret coronary microvessel in a pressurized no-flow state. Intrinsic tone was defined as the active increase in force or decrease in diameter with warming from 6°C to 37°C. Changes in force or diameter with various pharmacological agents were expressed as a percentage of intrinsic tone. Our results indicate that intrinsic tone accounts for 35% to 40% of total tone in all vascular preparations studied and is not dependent on extracellular calcium. Agents that increased cAMP levels (eg, forskolin, milrinone) and agents that decreased protein kinase C activity (eg, staurosporine) were partially effective in decreasing intrinsic tone. Nitroprusside, adenosine, hydralazine, and nifedipine had no significant effect.

Conclusions Our results indicate that intrinsic tone represents a significant component of vascular tone that has not been previously recognized and remains largely unexploited by current pharmacological therapies.

Key Words: blood pressure • muscle, smooth • vessels • hypertension

This article has been cited by other articles:

				D. H. Korzick, M. H. Laughlin, and D. K. Bowles Alterations in PKC signaling underlie enhanced myogenic tone in exercise-trained porcine coronary resistance arteries J Appl Physiol, April 1, 2004; 96(4): 1425 - 1432. [Abstract] [Full Text] [PDF]

				H.-M. Shin, H.-D. Je, C. Gallant, T. C. Tao, D. J. Hartshorne, M. Ito, and K. G. Morgan Differential Association and Localization of Myosin Phosphatase Subunits During Agonist-Induced Signal Transduction in Smooth Muscle Circ. Res., March 22, 2002; 90(5): 546 - 553. [Abstract] [Full Text] [PDF]

				P. Coats, F. Johnston, J. MacDonald, J. J. McMurray, and C. Hillier Signalling mechanisms underlying the myogenic response in human subcutaneous resistance arteries Cardiovasc Res, March 1, 2001; 49(4): 828 - 837. [Abstract] [Full Text] [PDF]

				M. B. Holmes, D. J. Schneider, M. G. Hayes, B. E. Sobel, and K. G. Mann Novel, Bedside, Tissue Factor-Dependent Clotting Assay Permits Improved Assessment of Combination Antithrombotic and Antiplatelet Therapy Circulation, October 24, 2000; 102(17): 2051 - 2057. [Abstract] [Full Text] [PDF]

				E. Thorin, D. Meerkin, O. F. Bertrand, P. Paiement, M. Joyal, and R. Bonan Influence of Postangioplasty {beta}-Irradiation on Endothelial Function in Porcine Coronary Arteries Circulation, March 28, 2000; 101(12): 1430 - 1435. [Abstract] [Full Text] [PDF]

				F.-X. Blanc, S. Salmeron, C. Coirault, M. Bard, E. Fadel, E. Dulmet, P. Dartevelle, and Y. Lecarpentier Effects of load and tone on the mechanics of isolated human bronchial smooth muscle J Appl Physiol, February 1, 1999; 86(2): 488 - 495. [Abstract] [Full Text] [PDF]

				D. K. Bowles, M. H. Laughlin, and M. Sturek Exercise training increases K+-channel contribution to regulation of coronary arterial tone J Appl Physiol, April 1, 1998; 84(4): 1225 - 1233. [Abstract] [Full Text] [PDF]

				H.-M. Shin, H.-D. Je, C. Gallant, T. C. Tao, D. J. Hartshorne, M. Ito, and K. G. Morgan Differential Association and Localization of Myosin Phosphatase Subunits During Agonist-Induced Signal Transduction in Smooth Muscle Circ. Res., March 22, 2002; 90(5): 546 - 553. [Abstract] [Full Text] [PDF]