EFFECTS OF 2450 MHZ CONTINUOUS WAVE MICROWAVE RADIATION AND ISOTHERMAL CONDUCTION ON CANINE PLATELET AGGREGOMETRY, SURVIVAL AND MARGINATION

JERROLD TALMADGE BUSHBERG, Purdue University

Abstract

The effect of 2450 MHz microwave radiation and isothermal conduction ex vivo exposures on canine platelets was analyzed (1) in vitro by studying adenosine-5'-diphosphate activated aggregation and (2) in vivo by studying the survival, distribution and physiological integrity of reinfused autologous Indium-111 labeled platelets. Platelet rich plasma (PRP) from eight healthy dogs was subjected to microwave irradiation at 10 mW/cm('2) and at 50 mW/cm('2) for 10, 100, 600, 900, 1800 seconds and at 100 mW/cm('2) for 10, 100, and 600 seconds. Isothermal conduction heat was applied to a paired sample with a conduction heating coil/oil bath system. Aggregometry analysis was performed immediately after exposure and 10 minutes post-exposure. No significant perturbations were observed following microwave exposure of 10 mW/cm('2). At higher power densities six specific types of aggregation phenomena were demonstrated: (1) Hyperaggregation, (2) Decreased Velocity Reduced Hyperaggregation, (3) Recovery, (4) Decreased Velocity Delayed Hyperaggregation, (5) Reversible Afunctionality, and (6) Irreversible Afunctionality. The absence of equivalent aggregation responses with isothermal conduction heating (extraisothermal effects) was attributed to differences in heating rate and not to nonthermal microwave-specific effects. Scintigraphic and survival kinetic studies were performed following power density/exposure time combinations of 10 mW/cm('2) for 30 minutes (I), 50 mW/cm('2) for 15 minutes (II), 50 mW/cm('2) for 30 minutes (III) and one sham exposed control (IV). PRP samples I and IV displayed normal survival half-times; however, exposure I resulted in a depressed 15-minute post-reinfusion circulating percentage (CP(,15)) of 29% compared to 61% for the control sample. Exposure of groups II and III resulted in a dramatic reduction in the CP(,15) (i.e. 18% and 1.3% respectively) and survival half-times. Margination of the labeled platelets was divided between the spleen, liver and blood pool. Dynamic scintigraphic images and region of interest computer analyses following catheter challenge demonstrated that while all animals were capable of some measurable degree of platelet deposition in the catheterized vessel, the largest catheterized-to-noncatheterized ratio (3.79) was achieved following the highest microwave exposure (group III).

Degree

Ph.D.

Subject Area

Biophysics

COinS