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J M Petrow

Publications and source records attributed to J M Petrow.

13 recordsLinked to original sources
PubMed1992

[Critique of Starling's hypothesis of the microcirculation].

By means of average estimation of the parameters on the capillary wall in experiments the capillary is supposed to content one pore only. This situation is not relevant to the practice of blood supply and leads to misinterpretation of the Starling's equation which can not represent the theoretical conception of the microcirculation in tissues. In order to avoid mistakes the usage of system theoretical analytic methods is indicated. This is the alternative way which is able to cover all kinds of preconditions of microcirculation in different tissues.

Blood Pressure↗
PubMed1992

[Critique of using the Staverman sigma reflection coefficient in the theory of microcirculation].

The usage of the reflection coefficient sigma defined by Staverman within the theory of microcirculation in tissues requires free perfusion through semipermeable membranes, which does not exist in the reality of tissue blood supply. In accordance to the principle of continuation of the hydraulics the reflection of colloidosmotic particles at semipermeable membranes in tissues does not comply with the condition of steady state regimes. Considering this fact the relevance of sigma in theoretical and practical investigations is challenged.

Animals↗
PubMed1991

[The introduction of thermodynamics in the theory of the microcirculation].

By application of thermodynamics on the theory of microcirculation in tissues one must implicate the fact that both phenomena convection and diffusion through semipermeable membranes take place in "non opened" compartments. Based on this precondition the present paper shows that the known calculations by Kedem and Katchalsky and others are insufficient in order to describe the above mentioned processes and that the reflection coefficient delta is not relevant to the real movement of molecules through capillary walls. Furthermore, the basic equation of the microcirculation is to be improved by a diffusion component in order to represent a better approximation of the exchange situation in tissues.

Capillaries↗
PubMed1991

[Formation and importance of lymph and edema in the organism].

In accordance to a new theory of microcirculation in tissues the lymphatic fluid is not a result of a imbalance between filtration and resorption across the capillary wall, but is rather a consequence of the protein recirculation in the following manner: blood vessels--interstitial space--lymphatic vessels--blood vessels. Convective and resorptive processes within the interstitium lead to local increase of the colloid-osmotic pressure, which only decreases by diffusion in the direction of lymphatic vessels and capillaries. In this way the lymphatics and the edema formation have a protective function concerning the physiological steady state of the tissue blood supply.

Blood Pressure↗
PubMed1990

[The theory of microcirculation. 4: The movement of molecules through semipermeable membranes].

The movement of the molecules through semipermeable membranes does not only follow thermodynamical principles but it is also in keeping with the classical mechanics of particle movement. Hence, in presence of chemical potentials a simple diffusion at semipermeable membranes is impossible because of additional convective fluid transport, which influences the process. Reversely, every solution passing through semipermeable membranes generates a certain pattern of chemical gradients. These findings are important for the calculation of protein distributions in tissues. The current view of application of thermodynamics on microcirculation includes several misinterpretations concerning the movement of molecules through semipermeable membranes, because it does not take into consideration the special preconditions. The present paper shows, that it is necessary to reinterpretate the current concept of this field of the microcirculation.

Animals↗
PubMed1990

[The theory of microcirculation. 3: Role of blood pressure amplitude on tissue microcirculation].

The blood pressure amplitude of the pulsatile blood supply evokes elastic interactions in the tissue, in which the noncompressible tissue fluid functions as mediator of strength. The particular morphological structure round the tissue capillary gives rise to the suggestion that in the result of these interactions a tissue pump is working which supports the blood flow as well as the exchange of substances at the capillary wall. The effectiveness of this pump depends upon the blood pressure amplitude, the heart rate and upon the elastic tissue properties and can be regulated with changes of these parameters. With the help of a hydraulic model an engineer-technical solution is built up and tested which in analogy to the tissue structure functions as pump and shows the properties of elastic interactions mentioned.

Blood Pressure↗
PubMed1990

[Theory of microcirculation. 2. Problems of microcirculation from the viewpoint of the new theoretical concept].

By means of network analysis and the use of a model which stimulates continuous blood supply to the tissue the basis of Starling's hypothesis of microcirculation is challenged. Contrary to the Starling's conception, we found that the microcirculation in the tissue is a stable process, whereby the interstitial hydraulic pressure (IHP) depends on the intracapillary blood pressure, on the permeability of the capillary wall, on the colloid-osmotic pressure and on the static pressure in the vessels and form a characteristic gradient along the capillary wall. The main effect of the colloid-osmotic pressure cannot be regarded as counteracting to the blood pressure, but instead consists in reduction of the IHP. Based on a theoretical conception about elastic interactions in the tissue a new method for measurement of the capillary filtration coefficients (CFC) is developed. Applying the method on the rabbit skeletal muscle the CFC is found to be 0.130 ml/min.mm Hg.100 g. This value is substantially higher than the values obtained from similar experiments reported in the literature (0.008 ml/min.mm Hg.100 g). The lymphatic fluid is not a result of a disbalance between filtration and resorption across the capillary wall, but it is a consequence of the protein recirculation in the following manner: blood vessels--interstitial space--lymphatic vessels--blood vessels. This recirculation is essential for the vital function of the tissue cells.

Animals↗
PubMed1990

[A new method for determining capillary filtration coefficients in tissues. 1. Methodologic principles].

A new method for measurement of the capillary filtration coefficient (CFC) is developed which avoids the errors of the known method of Pappenheimer and Soto-Rivera. The principle of our method consists in installation of the prepared tissue into a plethysmograph where it becomes exposed to a one step-pressure increase by which the tissue is pressed out. The CFC measurement is carried out by continuous weighing of the blood as it flows out of the arterial and venous parts of the prepared tissue vessels. The basic theoretical conception of this method is proven by means of tissue model.

Animals↗
PubMed1990

[A new method for determining capillary filtration coefficients in tissues. 2. Animal experiment studies].

A new method for the measurement of the capillary filtration coefficient (CFC), which avoids the errors of the previous methods, is proven experimentally. By applying the method to the rabbit skeletal muscle it is shown that the value of the CFC in muscle (0.130 ml/min.mm Hg.100 g) is substantially higher than the corresponding values which are found in the literature (0.008 ml/min.mm Hg.100 g). The results in the presented paper leads to some new conclusions about the theory of microcirculation in tissue. The CFC can be used as an indicator for the diagnosis and treatment control of circulatory diseases.

Animals↗
PubMed1988

New aspects of the theory of microcirculation.

New aspects and details of the mechanism of the microcirculation in the tissues are discussed in the paper. Particular attention is payed to the role of the blood pressure amplitude for the filtration and resorption processes through the capillary wall. A new model of the microcirculation is discribed in which the interstitial space is considered as a functional unit determining the intensity of the transcapillary exchange processes. The components of the hydraulic interstitial pressure are characterized as well as the process of formation and transport of limphatic fluid. The proposed model is a base for the better understanding of the theory of microcirculation.

Humans↗