Our objective is that of studying the spontaneous rhythmic constriction and dilation of the arterial and venous microcirculation termed vasomotion, and to determine: 1) the nature and origin of the phenomenon; 2) to establish how vasomotion is transmitted in the microvasculature; and 3) to explore the consequences of vasomotion for flow regulation and exchange. Our hypothesis is that vasomotion is in part, controlled by the myogenic properties of the microvasculature. We will test this hypothesis by studying vasomotion in the microcirculation of the hamster skin fold window preparation, where the ambient pressure of the animal is varied relative to that of the chamber. The chamber in the rat will be studied in order to observe subcutaneous muscle. The rabbit tenuissimus muscle will also be implemented since this preparation allows for the direct manipulation of input and output vessels, although it must be studied in an acute condition and during anesthesia. Measurements will include the dynamics of diameter changes, the characterization of the chamber vascular anatomy, blood flow in the microvessels and the direct measurement of pressure in the microvasculature along the continuous pathway of A1, A2, A3, and A4 sequence of branching. Vasomotion will be quantitated by a method called Prony Spectral Line Estimator to obtain data on amplitude, frequency, and phase. This will be utilized to measure the speed of propagation of the vasomotion waves, and whether they originate at specific foci that have the function of microvascular pacemakers. Studies will be extended to include the venous microcirculation. The speed of propagation of vasomotion will be compared to that of vasoconstrictor responses that are locally induced through the application of norepinephrine. The effects of vasomotion will be studied in terms of histograms of capillary flow in order to establish how vasomotion affects tissue perfusion. The effects on fluid exchange will be determined by relating the locally measured average capillary pressure to the colloid osmotic pressure of blood, to determine the difference in fluid balance between the active and inactive microcirculation. The hypothesis that pulsatile pressure influences vasomotion will be tested experimentally. This research finds application in the interpretation of whole organ experiments and the analysis of peripheral vascular resistance. The results of these kind of studies are significant to the understanding of hypertension, ischemia, and edema formation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL012493-19
Application #
3334488
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1975-05-01
Project End
1991-03-31
Budget Start
1989-04-01
Budget End
1991-03-31
Support Year
19
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Schubert, V; Schubert, P A; Breit, G et al. (1995) Analysis of arterial flowmotion in spinal cord injured and elderly subjects in an area at risk for the development of pressure sores. Paraplegia 33:387-97
Breit, G A; Intaglietta, M (1994) A modeling cross-spectral analysis technique based on the Prony Spectral Line Estimator (PSLE). IEEE Trans Biomed Eng 41:295-8
Bende, M; Arfors, K E; Intaglietta, M (1993) Nose drops induce vasomotion in the microcirculation of the sinus mucosa of the rabbit. ORL J Otorhinolaryngol Relat Spec 55:110-3
Schmidt, J A; Borgstrom, P; Firestone, G P et al. (1993) Periodic hemodynamics (flow motion) in peripheral arterial occlusive disease. J Vasc Surg 18:207-15
Akerlund, A; Arfors, K E; Bende, M et al. (1993) Effect of oxymetazoline on nasal and sinus mucosal blood flow in the rabbit as measured with laser-Doppler flowmetry. Ann Otol Rhinol Laryngol 102:123-6
Schmidt, J A; Borgstrom, P; Intaglietta, M (1993) The vascular origin of slow wave flowmotion in skeletal muscle during local hypotension. Int J Microcirc Clin Exp 12:287-97
Schmidt, J A; Borgstrom, P; Intaglietta, M (1993) Neurogenic modulation of periodic hemodynamics in rabbit skeletal muscle. J Appl Physiol 75:1216-21
Borgstrom, P; Schmidt, J A; Bruttig, S P et al. (1992) Slow-wave flowmotion in rabbit skeletal muscle after acute fixed-volume hemorrhage. Circ Shock 36:57-61
Schmidt, J A; Intaglietta, M; Borgstrom, P (1992) Periodic hemodynamics in skeletal muscle during local arterial pressure reduction. J Appl Physiol 73:1077-83
Bertuglia, S; Colantuoni, A; Coppini, G et al. (1991) Hypoxia- or hyperoxia-induced changes in arteriolar vasomotion in skeletal muscle microcirculation. Am J Physiol 260:H362-72

Showing the most recent 10 out of 46 publications