ABSTRACT-The mechanisms underlying the enhanced contractile response to phenylephrine (PE) and increased susceptibility to nifedipine of de-endothelialized thoracic aorta isolated from rats with dietary magnesium deficiency (Mg-deficient rats) were examined by functional and radioligand binding studies. Enhanced PE-induced contractions and increased susceptibility to nifedipine in Mg-deficient rats were not observed in the presence of 10 pM H7. PE significantly decreased the KD value without changing Bmax in the binding of [3H]PN200-110 to de-endothelialized aortic strips. The KD value obtained in the Mg-deficient rats was significantly smaller than that in the controls. Nifedipine displaced the binding of [3H]PN200-110 con centration-dependently, and the pK; value in Mg-deficient rats was significantly larger than that in the con trols. A combination of PE and H7 abolished this difference. These results indicate that the modulation of L-type Ca 21 channels via the stimulation of a,-adrenoceptors may be involved in the enhancement of vasoconstriction and increased susceptibility to nifedipine in aortas isolated from Mg-deficient rats. The H7-sensitive mechanisms may play an important role in these phenomena.

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ABSTRACT-The mechanisms underlying the enhanced contractile response to phorbol 12,13-dibutyrate (PDBu) were examined in de-endothelialized thoracic aortas isolated from rats with dietary magnesium (Mg) deficiency. PDBu (1.0 nM)-induced contractions were significantly larger in Mg-deficient rats than in the controls. The contraction was completely inhibited by nifedipine, removal of external Ca 21 or by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7). PDBu (1.0 nM) and phorbol 12-myristate 13-acetate (1.0 pM) significantly decreased the KD value and increased the Bmax for the binding of [3H]PN200-110 to the aortas. The degree of the decrease in the KD value was significantly greater in Mg-deficient rats than in the controls. The PDBu-induced decrease in the KD value was abolished by H7. These results suggest that activation of protein kinase C by phorbol esters may participate in the activation of L-type Ca 21 channels, which increases both the affinity of [3H]PN200-110 binding and the magnitude of the external Ca2+-dependent contraction. Dietary Mg-deficiency may enhance these processes.

SUMMARYSince images obtained from image sensor devices are commonly tested by performing a manual inspection or by means of procedures that involve large amounts of image processing, the growth in testing costs as the size of such devices increases poses a significant problem. Several approaches to automating the testing process have been proposed with a view to reducing testing costs but trial and error is needed to set the parameters required by such test procedures. In this paper we propose an error model for images taken by image sensor devices that can perform a quantitative evaluation with a small number of free parameters. Image quality testing can be performed relatively easily using this model since it replaces a previously ambiguous error model by one that can be determined uniquely. In addition, since the proposed error model is defined statistically in terms of the brightness levels of pixels in each of the individual images, even if there are individual differences between the image sensor devices, these have no influence on the testing procedure. Experimental results demonstrate that an image quality testing based on the proposed error model has the same level of accuracy as manual inspections performed by an experienced technician.

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