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We have studied the contribution of N-type voltage-dependent Ca2+ channels to both norepinephrine and epinephrine secretion from bovine chromaffin cells induced by high K+ or nicotine using omega-conotoxin GVIA, a selective blocker of N-type voltage-dependent Ca2+ channels. We found that high K+ (75 mM) induced catecholamine secretion was not affected by exposure of bovine chromaffin cells to omega-conotoxin GVIA (1 microM). However, nicotine-induced both norepinephrine and epinephrine secretion were similarly blocked (about 25%) by omega-conotoxin GVIA (1 microM). This effect could be explained by a potent (about 80%) and reversible blockade of the inward current induced by nicotine receptor activation in bovine chromaffin cells. The results indicate that besides the blockade of N-type voltage-dependent channels, omega-conotoxin GVIA is a potent and reversible blocker of the nicotinic receptor-induced currents in chromaffin cells.

We have studied the contribution of P-type voltage-dependent Ca2+ channels to both catacholamine (CA) and ATP secretion from bovine chromaffin cells induced by high K+ or nicotine using omega-agatoxin IVA, a selective blocker of P-type voltage-dependent Ca2+ channels. We found that high K+ (75 mM) induced the release of about 13% of norepinephrine, 5% epinephrine and 11% ATP, and that omega-agatoxin (100 nM) did not affect this secretion. However, both nicotine-induced CA and ATP secretion were significantly blocked (about 50%) by omega-agatoxin IVA (100 nM). In addition, this toxin also reversibly blocked (about 70%) the inward current induced by nicotine in bovine chromaffin cells. The results suggest that, besides its known action of blocking P-type voltage-dependent channels, omega-agatoxin is a potent and reversible blocker of the nicotinic receptor channel in chromaffin cells, and that this action would explain the blockade of nicotine-induced secretion.

The resting potential in adrenal medullary chromaffin cells is maintained by the activity of different K(+)-channels. Blockade of K(+)-channels should, at least in principle, lead to membrane depolarization, and the ensuing activation of voltage-gated Ca(2+)-channels should promote Ca2+ entry and catecholamine (CA) secretion. In support of this mechanism we found and report here that the K(+)-channel blocker tetraethylammonium (TEA) depolarized the chromaffin cell membrane, induced a substantial elevation in cytosolic [Ca2+], and a dose-dependent CA secretion reaching a maximum at 50 mM of approx. 10% of the total CA in the cells. In addition, TEA-induced CA secretion was found to be absolutely dependent on [Ca2+]o. In the presence of [Ca2+]o, TEA-stimulated CA release was blocked completely by elevated [MgCl2]o (12 mM), and inhibited in part by the Ca(2+)-channel antagonist nifedipine. The Ca(2+)-channel agonist Bay K-8644 markedly enhanced TEA-evoked CA release suggesting the involvement of L-type Ca(2+)-channels. Since, external application of TEA (30-50 mM) markedly blocked outward K+ currents but not inward currents carried by Na+ and Ca2+, we concluded that TEA stimulates CA secretion by blocking those K(+)-channels involved in the maintenance of the resting membrane potential.

Philadelphia chromosome-positive chronic myeloid leukaemia (CML) developed three years after the diagnosis of Waldenström macroglobulinemia (WM) in a patient who had received chlorambucil and prednisone during this time. Treatment with busulphan was started and two and a half years later the died in blastic crisis. Six months before the blastic transformation of the leukaemia the amount of IgM, which remains stable (above normal values) along the chronic phase, initiates a decrease, reaching normal values in the phase of acute transformation. CML is a very rare second neoplasia in patients receiving anticancer drugs. The correlation between the decrease of IgM and the blastic crisis is very interesting. We do not find an explanation for this finding although similar observations have been described heralding the appearance of second neoplasias in WM, and one might speculate with a possible role of IgM in the control of chronic phase of the myeloid leukaemia or if the overgrowth of blastic cells could overwhelm the development of lymphoplasmacytoid cells.

Three cases of postpartum acquired factor VIII inhibitors were seen in our hospital between 1981 and 1989. The clinical picture, which was mild in one patient and severe in two, began several months after delivery (four to nine). After treatment with methylprednisolone, good clinical response was obtained in the three cases. However, normal values of factor VIII:C were obtained more easily with the higher doses of steroids. A new pregnancy and delivery in one of our patients did not induce the reappearance of the inhibitor after several years of follow-up.

1 Transmural electrical stimulation (10 Hz, 40 V, 1 ms for 60s) increased total catecholamine secretion from perfused cat adrenal glands; this response was enhanced by neostigmine and inhibited by mecamylamine, suggesting that release of acetylcholine from splanchnic nerve terminals was stimulating nicotinic receptors and enhancing catecholamine secretion. 2 Isoprenaline, (-)-propranolol and (+)-propranolol (10(-7)-10(-5)M) inhibited the electrically-evoked secretory response by 40-70%; similar reductions were obtained with clonidine and yohimbine. Neither, (+)-propranolol nor (-)-propranolol inhibited K-evoked secretion from cat adrenals; in contrast, nimodipine potently inhibited it (IC50 = 24 nM). 3 Either, racemic propranolol or the (+)- or (-)-isomers (1-10 microM) equally inhibited [3H]-noradrenaline release evoked by nicotine or acetylcholine from cultured bovine adrenal chromaffin cells; clonidine (10 microM) inhibited secretion by 50% and yohimbine or isoprenaline did not affect it. 4 The results indicate that adrenomedullary catecholamine release evoked by splanchnic nerve stimulation is not modulated by alpha- or beta-adrenoceptors and suggest that propranolol may inhibit secretion by blocking ion fluxes through the acetylcholine receptor ionophore. Clonidine may inhibit secretion by this same mechanism, and/or by interfering with some intracellular event in the secretory mechanism.

Our study group consisted of 43 healthy preadolescence and adolescence of which 17 were boys and 13 premenarcheal and 13 postmenarcheal girls. Haematocrit, haemoglobin, serum iron, transferrin saturation, total iron-binding capacity, latent iron-binding capacity and serum ferritin were analyzed. Authors found that post-menarcheal girls are at lower levels than boys and that menstrual blood loss is a significant factor in determining iron status.

We have studied the correlation between [3H]ouabain binding sites, (Na+ + K+)ATPase (EC 3.6.1.3) activity and acetylcholine (ACh) release in different subcellular fractions of Torpedo marmorata electric organ (homogenate, synaptosomes, presynaptic plasma membranes). Presynaptic plasma membranes contained the greater number of [3H]ouabain binding sites, in good agreement with the high (Na+ + K+)ATPase activity found in this fraction. Blockade of this enzymatic activity by ouabain dose-dependently induced ACh release from pure cholinergic synaptosomes, either in the presence or absence of extracellular calcium ions. We suggest that one of the mechanisms involved in the ouabain-induced ACh release in the absence of Ca2+o may be an increase in Na+i that could (a) evoke Ca2+ release from internal stores and (b) inhibit ATP-dependent Ca2+ uptake by synaptic vesicles.

Serum testosterone, FSH, LH and prolactin levels have been determined in a group of 32 non-cirrhotic heavy drinkers at 9 and 21 h of the 1st, 3rd, 6th, 11th and 15th days after the onset of a florid ethanol withdrawal syndrome. In addition, serum steroid hormone binding globulin (SHBG) levels were determined at the 1st and 15th days. Serum levels of all these hormones were also determined in a control group of 15 healthy male volunteers. Serum testosterone levels, significantly lower in alcoholics at the beginning of the study, progressively increased along the observation period, recovering the circadian rhythm at the end of it. A significant increase was also observed in serum prolactin levels, in the low and upper limits of the normal range at the beginning and at the end of the study respectively. Serum FSH and LH levels were significantly higher in the alcoholics at the beginning of the study, with no significant variations during the observation period. There was a strong relationship between FSH and LH levels, but not between these hormones and testosterone. Thus, our data suggest that ethanol-induced hypogonadism is primary in origin, functional in nature and transient in its evolution.