Efflux carriers, modulation

Mols R, Deferme S, Augustijns P (2005) Sulfasalazine transport in in-vitro, ex-vivo and in-vivo absorption models contribution of efflux carriers and their modulation by co-administration of synthetic nature-identical fruit extracts. J Pharm Pharmacol 57 1565-1573. 

Figure 2. Comparison of (A) lr Cd from freshly isolated chick cerebral hemispheres exposed to a weak radiofrequency field (147 MHz, 0.8 mW/cm2), amplitude-modulated at low frequencies, and (B) 45C2 efflux changes from exposure to far weaker electric fields (56 V/m) in the same frequency spectrum from 1 to 32 Hz. The peak magnitude of the efflux change is similar for the two fields, but opposite in direction. For the radiofrequency field (A), the unmodulated carrier wave U had no effect when compared with controls C. Field gradients differ by about six orders of magnitude between (A) and (B) (22, 23).

In other experiments,+ he effect of temperature has been determined by measuring Ca efflux from chick brain tissue incubated at 32°C and 4l°C (3). When compared to 37°C, the efflux was 9% lower at 32°C and 15% higher at 4l°C. The temperature difference in control and irradiated samples could be experimentally controlled to less than 1°C, therefore temperature variation in the samples do not account for the 15-24% change in Ca efflux caused by exposure to 16 Hz modulated carrier waves. 

The field intensities, or wave amplitudes, that have produced changes in calcium-ion efflux at typical carrier frequencies and at typical modulation frequencies may be used to estimate the amount of nonlinearity that would be required to conform with observed results. Adey (1 1) has reported that a relatively small internal electric field intensity, on the order of 10"7 V/cm, at 16 Hz is sufficient to alter the binding of calcium ions in brain tissue. The internal field intensity of the carrier waves shown in Table 1 are on the order of 10-2 V/cm. From these observations, the ratio of the amplitudes of the first two terms in Equation (11) is... 

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