Moment theory for the analytical determination of rate constants for solute permeation at the interface of spherical molecular aggregates.

Moment equations were developed on the basis of the Einstein equation for diffusion and the random walk model to analytically determine the rate constant for the interfacial solute permeation from a bulk solvent into molecular aggregates (kin ) and the inverse rate constant from the molecular aggregates to the bulk solvent (kout ). The moment equations were in good agreement with those derived in a different manner. To demonstrate their effectiveness in one concrete example, the moment equations were used to analytically determine the values of kin and kout of three electrically neutral solutes, i.e. resorcinol, phenol, and nitrobenzene, from the first absolute (µ1A ) and second central (µ2C ) moments of their elution peaks, as measured by electrokinetic chromatography (EKC), in which the sodium dodecyl sulfate (SDS) micelles were used as a pseudostationary phase. The values of kin and kout should be determined with no chemical modifications and no physical action with the molecular aggregates because they are dynamic systems formed through weak interactions between the components. The moment analysis of the elution peak profiles measured by EKC is effective to unambiguously determine kin , kout , and the partition equilibrium constant (kin /kout ) under appropriate experimental conditions.

Changes in cardiovascular parameters and plasma norepinephrine level in rats after chronic constriction injury on the sciatic nerve.

To evaluate whether neuropathic pain affects autonomic nervous activities, we investigated daily change in cardiovascular parameters and plasma norepinephrine (NE) in free-moving rats after chronic constriction injury (CCI) on the sciatic nerve. Arterial blood pressure (BP), heart rate (HR), and the power spectrum of pulse interval variability were analyzed. Daily change in motor activity and nociceptive behavior was also measured from some CCI rats. In others, NE from daily blood samples was quantified and spontaneous pain was evaluated by daily monitoring of foot guarding behavior. We identified three stages in the daily change of cardiovascular parameters and plasma NE level over 3 weeks following CCI. The first stage (up to 3 days after the surgery) was characterized by increased MAP and HR, especially in the daytime, even though plasma NE was unchanged and motor activity decreased. The second stage (mid first to mid second postoperative weeks) was characterized by increased daytime MAP and HR, and the animals developed punctate hyperalgesia in the affected hindpaw. An NE surge that may have been related to spontaneous pain was present 3-5 days after CCI. The third stage, which appeared after the second postoperative week, was characterized by normalized MAP and decreased HR, and increased high-frequency (0.8-3.0Hz) power in pulse interval variability, which is an index of cardiac parasympathetic tone. These results demonstrated that cardiovascular function was kept high through sympathetic and non-sympathetic activity for 2 weeks after CCI, followed by a predominance of parasympathetic tone.