The Regulation of Pinocytosis in Mouse Macrophages

Abstract

A prior publication described the pinocytosis-inducing properties of a variety of both high and low molecular weight molecules (1). This study indicated that anionic molecules stimulated the formation of pinocytic vesicles whereas neutral and cationic species had in most instances little influence on this parameter of endocytic activity. Some of the most potent inducers proved to be macroanions and these molecules were thought to function by virtue of a physicochemical interaction with a membrane receptor. This view was suggested by the previous studies on the amoeba (2) and the similar molarities at which many of the macroanious stimulated a response in the macrophage system.One of the groups of macroanions studied in these experiments were the nucleic adds. Both ribonucleic and deoxyribonucleic acid enhanced vesicle flow in cultured mouse macrophages. This prompted further studies with both nucleic acid derivatives and high energy phosphate intermediates. This article will document the unique morphological and sfimulatory effects of adenosine and its Y-phosphates on macrophage pinocytic activity. Materials and MethodsThe preparation of macrophage cultures, enumeration of pinocytic vesicles, fixation and photographic procedures have been discussed (1,3). In these experiments cultures were maintained for either 24 or 48 hr in 50% newborn calf serum-No. 199 medium. Samples of newborn calf serum were obtained from either Microbiological

Purinergic signaling in inflammatory cells: P2 receptor expression, functional effects, and modulation of inflammatory responses

“…The influence of exogenous nucleotides on macrophages was identified by Cohn and Parks which paved the way for further research into the involvement of extracellular purine and pyrimidine nucleotides during inflammation [67]. The authors showed adenine nucleotides to be implicated in the pinocytic vesicle formation in mouse macrophage cultures.…”

Nucleotide receptors: an emerging family of regulatory molecules in blood cells

“…91 In this study the authors showed that addition of adenine nucleotides to a mouse macrophage culture resulted in a dramatic increase in pinocytic vesicle formation. After this early study, exogenous nucleotides as a stimulant for macrophages were basically neglected for several years and resurrected only in 1985 by Silverstein and coworkers, 92 who reported that extracellular ATP inhibited Fc receptor-mediated phagocytosis and at the same time caused influx of Na ϩ , efflux of K ϩ , and an increase in [Ca ϩϩ ] i .…”

Molecular Physiology of P2X Receptors

“…These include membrane current (43, 47, 63, 87, 118, 171, 227, 268, 332-335, 344, 380, 446, 484), increase in [Ca 2ϩ ] i (23,88,132,157,202,402,406), uptake of fluorescent dyes (65,168,184,185,202,402,427,438,444,446), membrane blebbing or other morphological change (80), spontaneous cell fusion (65,125), interleukin processing and release (43,129,130,155,158,366), activation of NF-B (131,133), killing of Mycobacterium tuberculosis (260,267,422), activation of p38 MAP kinase (186), activation of phospholipase D (111,112,200), formation of multinucleate giant cells (65,125), and various measures of cell death (see Ref. 100).…”