Reversible and irreversible alterations of the optical thickness of PQ/PMMA volume recording media samples. Part 2: mathematical modeling.

A theoretical study of phenanthrenequinone-doped polymethyl methacrylate (PQ/PMMA) samples parameter changes during irradiation is presented. The research has been carried out on the basis of the experimental study (Part 1, [Appl. Opt.

Reversible and irreversible alterations of the optical thickness of PQ/PMMA volume recording media samples. Part I: Experiment.

Experimental research into changes of the optical thickness of phenanthrenequinone-doped polymethyl methacrylate samples in the process of irradiation by a 473 nm laser is presented. It was demonstrated that heating-induced reversible changes lead to a decrease in the optical thickness. The temperature coefficient of the relative changes of the optical thickness was measured to be -1.

[Allosteric effect of serotonin and mianserin on the kinetics of specific [3H]-ligand binding to adrenergic and muscarinic receptors in the rat cerebral cortex membranes].

The effects of serotonin receptor activation (by serotonin) and inhibition (by mianserin) on the properties of the α1-, α2-adrenoreceptors, and muscarinic cholinergic receptors in subcellular membrane fractions from the rat cerebral cortex were studied. Experimental data on the kinetics of specific antagonists binding to adrenergic and muscarinic receptors were analyzed by graphical and mathematical methods. The results suggest the presence of allosteric (cross-talk) interaction.

[Intracellular transmission of the cholinergic signal in the chick amnion].

The role of the system of deposited calcium in the mediation of contractile reactions to carbachol in an isolated amnion of 11-13 day old chicken embryo was studied. It was found that thapsigargin (2 microM, 20 min), an inhibitor of the endoplasmic reticulum Ca2+ -ATPases, decreases the tonic reaction to carbachol by 40 +/- 2%. In the presence of U73122 (5-10 microM, 10 min), a phosphoinositide-specific phospholipase C inhibitor, the rhythmic contractile reaction of the amnion to carbachol is blocked, whereas the tonic reactiondecreases to 47 +/- 9% of the initial one.

[Similarities and differences in the effect of cocaine on alpha-adrenergic and muscarinic response].

Similarities and differences in the effect of cocaine on alpha-adrenergic and muscarinic receptors were shown in three experimental models. The postsynaptic stimulating effect of cocaine through activation of alpha-adrenergic receptors was found in a chicken embryo without innervation and in an innervated rat vas deferens. Cocaine caused an increase of the amount of activated alpha-adrenergic receptors and the appearance of an additional receptor pool and changed their dimerization level.

[Effect of rabbit adaptation to cold on the depressor muscarinic cholinergic reaction of the arterial pressure of the hind limb vessels and the small intestine in situ and the systemic arterial pressure].

Modification of the main parameters of cholinergic reactions in rabbits, i.e., of the specific sensitivity to agonists (EC50), maximal reaction values (Pm) of arterial pressure in the hind limb vessels and small intestine in situ, and systemic arterial pressure after adaptation to cold for 1, 5, 10, and 30 days has been investigated.

[The effect of cocaine on kinetics of alpha1-adrenergic contractile response in different portions of the rat vas deferens].

The effect of cocaine (10 microM) on the kinetics of contractile response to noradrenaline (NA) was studied in the rat epididymal and prostatic vas deferens. Cocaine caused an acute increase in vas deferens adrenergic sensitivity primarily due to blockage of NA neuronal capture. The presynaptic action prevailed in the epididymal half: the EC50 value decreased 32-fold with a slight increase of the maximum adrenergic response more evident in the prostatic half.

[The significance of extracellular Ca2+ in contractile responses in chick amnion].

Neurotransmitter receptors are formed during chick embryo development in the amnion, an avascular extraembryonic membrane devoid of innervation. Carbachol induces phasic and tonic contractions mediated by M3 cholinoceptors in an amniotic membrane strip isolated from 11-14-day-old chick embryo. The carbachol effect on the amnion contractile activity was studied in normal physiological salt solution, during depolarization by K+, exposure to nifedipine, and in calcium-free medium.

[Effect of elevated extracellular K+ on the kinetics of alpha 1-adrenergic contractile response in the rat vas deferens].

Increase in KCl concentration from 5.5 to 15.5 mM in physiological solution produces potentiation of contractions in response to phenylephrine-mediated by alpha 1-adrenoceptors in the rat vas deferens.

[Muscarinic acetylcholine receptors of the chick amnion].

The presence of muscarinic (M) acetylcholine receptors in the noninnervated chick amnion makes it possible to analyze their functioning with presynaptic effects excluded. The M receptors of the amnion mediating its contraction were identified by testing with selective antagonists: pirenzepine for M1, methoctramine for M2, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) for M3, and tropicamide for M4 receptor subtype. All antagonists acted as competitive inhibitors of M-acetylcholine receptors.

[Effect of cold adaptation of alpha- and beta-adrenergic responses of blood pressure in hindlimb and small intestine in situ and systemic blood pressure in rabbits].

Changes in the main parameters of alpha- and beta-adrenergic responses, sensitivity to agonists (EC50) and maximum response (Pm) of hindlimb and small intestinal blood pressure in situ and systemic blood pressure were studied in rabbits adapted to cold for 1-30 days (daily exposures to -10 degrees C for 6 h). The responses to phenylephrine, noradrenaline. adrenaline, clonidine (alpha-agonists), and isopropylnoradrenaline (beta-agonist) corresponded to the equation p = (PmAn)/(EC50n + An) with n = 1 and n = 2, respectively.

[Changes of alpha1-adrenergic and muscarinic cholinergic responses of arterial blood pressure in the rabbit during adaptation to cold].

Changes in major parameters of alpha1-adrenergic and muscarinic cholinergic responses of arterial blood pressure (EC50 and P(m)) were studied in rabbits adapted to cold for 1-30 days (daily cold exposures for 6 hours at -10 degrees C). It was shown that responses to noradrenaline, adrenaline (agonists of alpha1-adrenoceptors) and acetylcholine (agonist of muscarinic cholinoreceptors) could be expressed by equation p = (Pm- A(n))/(EC50(n) + A(n)) with n = 1. Adaptation to cold induced radically different changes in the major parameters of adrenergic and cholinergic responses.

[Influence of carbachol on the kinetic parameters of the contractile response to noradrenaline in the rat vas deferens].

Graphic and mathematical analysis of kinetics of the rat vas deferens contractile response to noradrenaline showed that alpha1-adrenoceptors mediating the contraction were in different functional states. In some organs, these receptors were homogeneous with the Hill coefficient n = 1 (the linear mode of the Scatchard plot), in the others--not homogeneous, with n > 1 (not linear mode of the Scatchard plot). Carbachol increased the contractile response to noradrenaline.

[Carbachol effect on kinetics of the alpha1-adrenergic contractile response of the rat vas deferens].

Analysis of the control kinetics of the rat vas deferens contractile response to phenylephrine showed that alpha 1-adrenoceptors mediating the contraction could be in different functional states. In some organs these receptors represented a single pool with Hill coefficient n = 1 (the linear mode of the Scatchard plot), in others--not a single pool, n > 1 (not linear mode of the Scatchard plot). Activation of muscarinic cholinergic receptors by carbachol exerted a stimulating effect on the alpha 1-adrenergic contractile response especially to low adrenomimetic concentrations and the maximum response was increased.

[Effect of adaptation to cold on the alpha1- and beta-adrenergic reactions of arterial vessels of the small intestine in rabbits].

Changes in major paraments of alpha 1- and beta-adrenergic responses (EC50 and Pm) were studied in the intestine arterial blood vessels of rabbits adapted to cold for 1-30 days (daily cold exposures for 6 hours at -10 degrees C). It was shown that responses to phenylephrine, noradrenaline, adrenaline (alpha 1-agonists), isopropylnoradrenaline (beta-agonist) corresponded to the equation p = (Pm.An)/(EC50n + An) with n = 1 and n = 2, respectively.

Analysis of ligand-receptor interactions from the molecular level to the whole-body level.

A system for the quantitative analysis of ligand-receptor interactions is presented, based on models of different levels of complexity. For two pools of receptors, binding of a radioactive ligand is described by b = [(Bml x A(nl))/(K(nl)dl + A(nl))] + [(Bm2 x A(n2))/(Kn2(d2) + A(n2))], (1) where b is the number of bound receptors at a ligand concentration [A], Bml and Bm2 are the receptor concentrations. Kdl and Kd2 are dissociation constants for the ligand-receptor complex, and n1 and n2 are Hill coefficients.