Summary of papers presented at the ninth meeting of the Japanese society for microcirculation

Summary of papers presented at the ninth meeting of the Japanese society for microcirculation

MICROVASCULAR RESEARCH 28, 395-396 (1984) MEETING REPORT Summary of Papers Presented at the Ninth Meeting Japanese Society for Microcirculation o...

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MICROVASCULAR

RESEARCH

28, 395-396 (1984)

MEETING REPORT Summary

of Papers Presented at the Ninth Meeting Japanese Society for Microcirculation

of The

M. ASANO Department of Physiological The Institute of Public Health,

Hygiene, Tokyo, Japan

The ninth meeting was held on February 4 and 5, 1984, in Tokyo, where an invited lecture and 46 free communications were presented. Almost half of the papers (22 articles) were concerned with organ microcirculation, and the remaining half (24 articles) consisted of theoretical, experimental, and clinical research relating to microhemodynamics, microhemorrheology, diabetology, lymphology, and other fields. In his lecture, Professor I. C. Roddie mentioned that when flow and pressure are measured in a peripheral lymphatic vessel in sheep or man, lymph flow is not continuous but comes in spurts which are not related to skeletal muscle contractions or other external forces, and suggested that intrinsic pumping by lymphatic smooth muscle may be more important than extrinsic forces in lymph transport. On the other hand, E. Sekizuka et al. showed that the regular contractile nature of peripheral lymphatic vessel observed in the rat mesentery can be recorded as a sine curve-like wave of successive plotting of changes in diameter of a single lymphangion, and that dimensional changes of the neighboring lymphangions have a good cross-correlation between them according to analysis of periodicity of the contractile movements and time lag of the lymphatic activity between the two points of adjacent lymphangions. Both papers stimulated fresh interest in the dynamic transport of lymph due to the local regulatory mechanism of lymphatic smooth muscle cells. One of the most interesting papers on microhemodynamics was the work of M. Shibata et al., who suggested a cascade-type regulation of the local metabolic and the central neural control mechanism on the microcirculation of skeletal muscle. They investigated effects of local tissue PO2 and autonomic stimuli on capillary blood velocity and on density of perfused capillaries in the rabbit tenuissimus muscle. The data revealed that the reflex effect on both velocity and density at 20 mm Hg PO* was some 1.3 and 4.3 times enhanced at 80 mm Hg PO*, respectively. Another interesting paper was presented by S. Oka, who extended theoretically the application of optimality principles to microvascular ramification. The anatomical calculations indicated that the bifurcation angle lies 395 00262862/84 $3.00 Copyritzht 0 1984 by Academic Press, Inc. All rights of reproduction in any form reserved. Printed in U.S.A.

396

MEETING

REPORT

between 37” and 49”, and that the relative diameter of the daughter branches to their parent vessels lies between 0.758 and 0.794 when the daughter vessels ramify with symmetry in angle and with equal diameters. In the field of organ microcirculation, M. Nakamura et al. proposed valuable autoradiographic evidence that indicated localization of the muscarinic cholinergic receptors in the basal two-thirds of the gastric mucosa of rats, especially near the parietal and chief cells and true capillaries. This implies the importance of cholinergic autonomic nervous participation in the gastric mucosa in relation to the pathogenesis of acute gastric ulcer. In this connection, N. Sato et al. also presented results on gastric mucosal blood flow in rats. Using an organ reflectance spectrophotometer they found that vasodilators such as acetylcholine and isoproterenol cause an increase in the mucosal blood flow and tissue oxygen simultaneously, while secretagogues such as tetragastrin and histamine do so in the blood flow without any change in the tissue oxygen. A paper on the differential vasodilating responses to CO2 and papaverine in the cat brain was presented by M. Tomita et al. They measured cerebral blood flow using a photoelectric method which they developed. The analysis of intravascular transference of blood was based also upon a method of tissue indicator dilution they developed. The data suggest that the cerebral cortex microvasculature becomes equally perfused during CO, inhalation, while it becomes heterogenously perfused after papaverine injection. Anatomical observations by Y. Katsume et al. on the sinus hair follicle of rabbits were obtained with light and electron microscopy. A so-called endothelial cytoplasmic bridge of the cavernous sinus was observed, of which a characteristic feature is a cytoplasmic process of an endothelial cell extending to another endothelial cell transversing the capillary lumen and conjugating to each other. They speculated that the cytoplasmic bridge may play a role in hemodynamic regulation and contribute to constant retention of a large amount of blood in the ring sinus. From the methodological point of view two papers were worthy of notice. The first was presented by S. Sakaguchi et al., who introduced a camera-type planimeter gauge for continuous measurement of dimensions of blood or lymphatic vessels in vitro. This device was constructed with an area image sensor installed into a monocular reflex camera with a microcomputer, and was reported to have the following advantages: possibility of contact-free measurement, high resolving power of 4100 pm2 in principle, and capacity of displaying eight images of vessel on both oscillograph and printer simultaneously. The second was a paper by M. Yoshida et al., who demonstrated a new method for measuring the capillary surface area product (PS) in vivo. They recorded photoelectrically the rate of the indicator washout from tissue to capillary in the tenuissimus muscle of rabbits on a VTR monitor connected to a microscope, and calculated the PS value based ~9 the time constant of the clearance curve and the blood concentration of the indicator. They also confirmed the possibility of applying the image processing techniques of TV signals to this method to carry out simultaneous measurements of the PS in various tissue sites on the microscopic field.