Cytofluorometric Analysis of Anaphylactic Secretion of 5-Hydroxytryptamine and Heparin from Rat Mast Cells

Abstract

Actively sensitized rat mast cells were stimulated to secretion in vitro by means of an anaphylactic IgE antigen reaction or with polymyxin B. Release of 5-hydroxytryptamine (5-HT) and heparin from the cells and from individual granules, extruded or displaced from stimulated cells with micromanipulation, was quantitated cytofluorometrically. Several similarities in action between the two secretagogues were found. All extruded and some intracellular granules from stimulated cells lacked 5-HT, and no heparin was released from the granules. Heparin secretion from mast cells was due to granule extrusion alone. Further, the proportions between 5-HT and heparin released from mast cells indicated that amine release, too, is mainly, but not exclusively, associated with overt granule exocytosis. The results suggested that the first extruded granules are the richest in both 5-HT and heparin. Antigen-induced secretion was not as vigorous as that induced by polymyxin and, unlike the latter, followed after a short lag of about 20 sec.

5-Hydroxytryptamine (5-HT)2Receptor Involvement in Acute 5-HT-Evoked Scratching but Not in Allergic Pruritus Induced by Dinitrofluorobenzene in Rats

“…Intradermal injection of other agents that induce itch in humans, such as histamine, compound 48/80, substance P, and proteases, elicited little or no scratching in Sprague-Dawley rats (Thomsen et al, 2001;Jinks and Carstens, 2002). Rodent mast cells contain relatively high concentrations of 5-HT (Gustafsson, 1980;Graziano, 1988;Purcell et al, 1989), consistent with a role for 5-HT as an itch mediator in rodents.…”

Opioid Modulation of Scratching and Spinal c-fosExpression Evoked by Intradermal Serotonin

“…Previous reports that opiates can exacerbate itch sensation in humans (Lanz et al, 1982;Stenseth et al, 1985;Ballantyne et al, 1988) would predict an increase in 5-HT-evoked scratching, which was not observed presently. 5-HT is an inflammatory mediator associated with pain and hyperalgesia (Jensen et al, 1991;Taiwo and Levine, 1992;Abbott et al, 1996) and is liberated from rodent mast cells and platelets in many inflammatory responses (Gustafsson, 1980;Purcell et al, 1989). In humans, intradermal injection (up to 20 g/20 l) (Keele and Armstrong, 1964;Fjellner and Hägermark, 1979;Hägermark, 1995) or iontophoresis of 5-HT (1%) (Weisshaar et al, 1997) is weakly pruritic.…”

Fluorescent Berberine Binding as a Marker of Secretory Activity in Mast Cells

“…We have used a cy tofluorometric method to measure heparin release [Gimimsori and Enerback. 1980;Gustavsson, 1980] utilizing the weakly fluorescent dye, berberine, which strongly increases its quantum yield of fluorescence upon binding to heparin. This method can be used to measure the heparin content of individual mast cells by microscopic fluorometry [Enerback.…”