Inhibition of exocytosis by intracellularly applied antibodies against a chromaffin granule-binding protein

s-cyclophilin is retained intracellularly via a unique COOH-terminal sequence and colocalizes with the calcium storage protein calreticulin.

“…Rat liver subcellular fractions were isolated by a procedure that had been specifically devised to yield Cat+ transport competent microsomes (Dawson, 1982) . Bovine adrenal medulla derived secretory granules were prepared as described (Schweizer et al ., 1989) .…”

Calcium requirements for secretion in bovine chromaffin cells.

“…A possible additional complication is that studies on chromaffin cells (Perrin et al 1987;Schweizer et al 1989;Eberhard et al 1990; Burgoyne, 1990), other endocrine cells (Thomas et al 1990) and neurons (reviewed in Kelly, 1988) suggest that there might be a relatively small pool of membrane-docked, release-ready vesicles that can be exocytosed at high rates. This idea is consistent with several observations we have made (see also and can be used to interpret some of our findings.…”

“…The rapid initial bout of secretion may be due G. J. A UGUSTINE AND E. NEHER to the presence of a limited population of chromaffin granules that are present at the membrane and are rapidly releasable, while the slower late phase of secretion may be limited by a slower mobilization of vesicles toward the release sites at the membrane (Perrin, Langley & Aunis, 1987;Schweizer et al 1989;Eberhard, Cooper, Low & Holz, 1990;Thomas et al 1990). The relationship between the changes in [Ca2+]i and the maximum slope of the increase in Cm caused by these agents is shown in Fig.…”

“…One of the most interesting applications of the patch clamp in the study of exocytosis is to deliver molecular probes to the interior of secretory cells (Fernandez, Neher & Gomperts, 1984;Penner et al 1986;Schweizer et al 1989). However, the presence of wash-out requires careful experimental design, to avoid confusing washout during probe delivery with an actual inhibitory action of a probe.…”

Intracellular calcium and vasopressin release of rat isolated neurohypophysial nerve endings.

“…A number of additional possibilities could participate in regulating the time course of AVP secretion to maintained depolarization. For example, the secretory time course could be related to depletion of a readily releasable pool of predocked secretory granules which then must be refilled by mobilization of granules from an adjacent or interior site within the nerve ending (Schweizer et al 1989). This possibility has been repeatedly discussed and discounted for a number of cell types based on the ability to re-evoke secretion by addition of Ca2+ ionophores (Nordmann, 1976;Birman & Meunier, 1985) or by determining that the percentage of product secreted represented a small percentage of the total product present (Nordmann, 1976).…”