Activation of phospholipase C and guanylyl cyclase by endothelins in human trabecular meshwork cells.

Purpose: To characterize effects of endothelins on activities of phospholipase C (PLC) and nucleotide cyclases in human trabecular meshwork (TM) cells.

Methods: Cultured simian virus 40-transformed human TM (HTM-3) or non-transformed (HTM-16) cells were used. Changes in the PLC activity were determined by assaying the production of [3H] inositol phosphates.

Pharmacological characterization of an FP prostaglandin receptor on rat vascular smooth muscle cells (A7r5) coupled to phosphoinositide turnover and intracellular calcium mobilization.

An FP prostaglandin (PG) receptor on the A7r5 rat aorta smooth muscle cell line has been characterized by assays of phosphoinositide (PI) turnover and intracellular calcium mobilization stimulated by structurally diverse PGs. In the PI turnover assay, cloprostenol was the most potent PG tested, with a potency (EC50) of 0.84 +/- 0.

Histamine induced contraction of human ciliary muscle cells.

In cultured human ciliary muscle cells we previously showed that histamine, via an H1 receptor, stimulates the production of inositol phosphates and mobilization of intracellular calcium. We further investigated in this study whether histamine would cause contraction of human ciliary muscle cells. Photomicrographs were taken of the ciliary muscle cells before and after exposure to histamine.

Human conjunctival epithelial cells express histamine-1 receptors coupled to phosphoinositide turnover and intracellular calcium mobilization: role in ocular allergic and inflammatory diseases.

Dispase-dissociated primary cultures of human conjunctival epithelial (HCE) cells were stimulated with histamine and the generation of inositol phosphates ([3H]IPs) from [3H]phosphoinositide (PI) hydrolysis and the mobilization of intracellular calcium ([Ca2+]i) were studied using ion exchange chromatography and Fura-2 fluorescence techniques, respectively. Histamine (100 microM) maximally stimulated PI turnover in HCE cells by 210 +/- 10% (n = 21) above basal levels and with a potency (EC50) of 3.3 microM (n = 4).

Effect of histamine on phosphoinositide turnover and intracellular calcium in human ciliary muscle cells.

This report describes the effect of histamine on phospholipase C (PLC) activity and calcium mobilization in cultured human ciliary muscle cells. PLC activity was assessed by measuring the production of inositol phosphates and intracellular calcium mobilization was assessed by Fura 2 ratio fluorometry. The stimulation of PLC by histamine was concentration dependent with an EC50 of 0.