Decompression aggregation and compression non-aggregation of human platelets

82

ABSTRACTS

TITLE:

DECOMPRESSION AGGREGATION AND COMPRESSION NON'AGGREGATION OF tIUMAN PLATELETS

AUTIIOR:

M. Murayama, Ph.D.

AFFILIATION:

Laboratory of Cellular and Developmental Biology, National institute of ltealth, Bathesda, Maryland 20~92

INTRODUCTION. A theory of stmntant~us aggregation of lluman platelets by decompression has been derived from the observation tltat the molecular volume of activation for the process of fibrin polymerization is a large positive number. Therefrom it was deduced that the rate of fibrin polymerization could be accelerated by decompression (76B down to 380 tort)t3), From this observation the theory of spontaneous aggregation of human platelets was derived. Tile theory has bean experimentally tested and confirmed by producing spontaneous aggregation of p!atelets independent of PO~{1}o "1"he corollary to the theory is that platelet's do not aggregate when compressed by a hydraulic press at 681) atmosptlere (ATM) and then fixed in sit u (2). METIIODS, Piatelcts rich plasma (PRP) was prepared by means of a platelotphetesis apparatus. Platelet counts were obtained by use of a Coulter Counter and the concentration adjusted to 50tl,000 per microliter. The differential interference optical microscope (NIKON] was used. To investigate the influence of PO2 on spontaneous aggregation of human platelcts by decompression a tonometer cuvette was used. after equilibrating for 20 minutes with air, or 95% 02 - ~ CO7 or 95~ N2 - 5~ CO~, and evacuated to 380 tort. The ~ggregation rate wag monitored with a recording spectrophotometer (Cary 14) at 380 nm (see Fig.I. For this investigation of compression non-aggregation of human platelets fixed in situ under high hydraulic pressure, a two-compartment cylinder was used. The cylinder is open-ended with a cover glass 0.15 mm thick as a partition in the middle to obtain two compartments. Each c~mpartment was filled with fluid, PRP in one and 2% glutaraldehyde in the other, and both ends were covered with latex rubber sheeting. The cylinder was pressurized for 30 minutes at lO.OO0 PSI. Then by a special arrangement (2), tile plate!ors were fixed in site with glutaraldehyde and from the ¢~'et preparations. the platelets were then photomicrographed. RESULTS. It was demonstrated experimentally that human platclcts aggregate spontaneously independent PO~ (see t a b l e t . It was also shown that human pla~elets do not aggregate when compressed to 680 ATM and fixed in sttu.

CONCLUSION. "/'his study shows experimentally that decompression causes spontaneous aggregation of human platelets, based on a ti~eory of pressure effect on fibrin polymerization. Pressure effects on platelets can be explained by the principle of Le Chatelier. The corollary to the above is that platelets cannot aggregate under high h y d r a u l i c pressure (680 ATM).

REF_m~ENCES. I. ~4urayama, M: Ex viva human platolet aggregation induced by decompression during reduced barometric pressure, hydrostatic and hydrodynamic (Bernoulli) effect. Thrombosis Res 33:477-485, 1984 2, Murayama, M: Compression non-aggregation of human platelets fixed in sj!U under high hydraulic pressure. Thrombosis Res, in press. 3. Murayama, M: The rate of fibrin polymerization accelerated by decompression. In press.

lJJ

tJ Z <:

760

0.6,

253 torr

03 I~ <

tort

0,5'

0.4 I . . . . . . . 0

"

, !

-

, 2

.......... 3

TIME (Hours)

DECOMPRESSIONPLATELETAGGREGATION Gas

is independentof PO2 Pressure Po2 Aggregation (Arm.) (Tort) Index

Air 2 0 . 9 % 0 2 . 7 9 A % N 2 . . . . . .

"1 1/2

149 69

0 ++++

95%02.5%C02 . . . .

1 112

677 316

0 +÷++

95%N2.5%CO2 . . . .

1 1t2

0 0

0 ++++

++++ denotes platlet aggregation.