Effect of nicotine on vasoconstrictor and vasodilator responses in human skin vasculature.

Our objective was to test the hypothesis that acute exposure of human skin vasculature to nicotine may have deleterious effects on endothelial function. Vasoconstriction and vasorelaxation in isolated perfused human skin flaps (approximately 8 x 18 cm) derived from dermolipectomy specimens were assessed by studying changes in skin perfusion pressure measured by a pressure transducer, and skin perfusion was assessed by a dermofluorometry technique (n = 4 or 5). It was observed that nicotine (10(-7) M) amplified (P < 0.

Characterization and partial purification of rat submandibular gland protein kinase C.

Membrane-bound protein kinase C of rat submandibular gland was characterized and the cytosolic kinase C of the tissue was partially purified. The membrane-bound kinase could be activated by Triton X-100 but not EGTA in the presence of both Ca2+ and phosphatidylserine (PS). The Km values for Ca2+ and PS were 150 microM and 5 micrograms, respectively.

Digitalis-like biological activity in rat cerebellum.

The cytosolic fraction of rat cerebellum possesses a factor(s) which is capable of inhibiting synaptosomal Na,K-ATPase activity, competing with [3H]ouabain binding to rat brain synaptosomes, and inducing positive inotropy in guinea pig atrial strips. These results demonstrate the existence of a ouabain-like principle in rat cerebella. The inhibitory activity of the factor was found to be partially thermolabile and diminished by a proteolytic agent, and the activity could be augmented by increasing concentrations of Mg2+, suggesting a regulatory mechanism for the endogenous digitalis-like principle.