Facts and Hypotheses

The phenomenological description of the excitability phenomenon given in Section 1.3 cannot claim to contain a final solution to the problem of the nature of transport systems of biological membranes responsible for nervous impuse generation. Where we stand, we can only conclude that the membrane as a whole is a nonlinear ion conductor whose properties are largely dependent upon the electrice field. For all that, the fact that the use of certain specific blocking compounds—tetrodotoxin and tetraethylammonium—allows the sodium and potassium ionic currents to be separated is alone sufficient to support the conception of selective transport systems located in the lipid matrix 

The number of transport systems per unit surface area for Na and K ions has been estimated according to the bound amounts of the specific blocking agents—tetrodotoxin and saxytoxiii—as well as by measuring the ionic current fluctuations. For example, a muscle cell membrane contains around 400 sodium transport systems per 1 micron. Conductance of each transport system is about 4 x 10 (for sodium) and 12 x 10 (for potassium). 

By now there is plenty of evidence in favor of the fact that the conducting structures of membranes behave like channels rather than mobile carriers. 

The reason for using a special kind of subunits in this particular model is that, for example, such enzymes as pronase can eliminate sodium channel inactivation without affecting its conductance. Generally speaking, the gate itself might be performing the function of field sensor, but the portion of 

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W. Kostowski (1981). Brain noradrenalin, depression and antidepressant drugs facts and hypotheses. Trends Pharmacol. Sci. 2 314—317. 

Rizzuto R, Pinton P, Ferrari D, Chami M, Szabadkai G, Magalhaes PJ, Di Virgilio F, Pozzan T (2003) Calcium and apoptosis facts and hypotheses. Oncogene 22 8619-8627. 

Santella, L., 1998, The role of calcium in the cell cycle facts and hypotheses. Biochem Biophys Res Commun 244, 317-24. 

Singleton, V. L. (1995). Maturation of wines and spirits Comparisons, facts, and hypotheses. Am. Enol. Vitic. 46, 98-115. 

V.L. Singleton, Maturation of Wines and Spirits—Comparisons, Facts, and Hypotheses, Amer. J. Enol. Viticult. 46(1), 98-115 (1995). 

A. Gougeon Regulation of ovarian follicular development in primates facts and hypotheses. Endocrine Review 17, 121(1996). 

Shmukicr, Y, B., and Bu/.nikov, G, A. (1998). Functional coupling of neuroiran.smitters with second messengers during cleavage divisions Facts and hypotheses. Perspecl. Dev. NeumhioL 5, 469-t83,... 

We shall attempt in this review to summarize some facts and hypotheses concerning the mechanisms by which heme and chlorophyll are controlled at the first step of the biosynthetic chain—namely, at the level of the formation of (5-aminolevulinic acid (ALA). No complete literature review is intended. A few of the more comprehensive recent references are given in the first part of the bibliography [1-12]. 

The development of successful methods for preparing such structures has been a challenge to the synthetic chemist. The remarkable chemistry of the processes discovered has also led to significant new facts and hypotheses about the behavior of phenoxy radicals. 

Plotz, F.B., Slutsky, A.S., VanVught, A.J., and Heijnen, C.J. 2004. Ventilator-induced lung injury and multiple system organ failure A critical review of facts and hypotheses. Intensive Care Med 30 1865-72. 

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