Nifedipine overdose accompanied by ethanol intoxication in a patient with congenital heart disease

A 34-year-old female was brought to the emergency department after taking 200 to 250 mg of nifedipine and drinking an unknown amount of ethanol in a suicide attempt. She was hypotensive, acidotic, mildly hyperglycemic, and exhibited a conduction abnormality on the ECG. The patient was treated with IV fluids, thiamine, and calcium infusion. The patient was later found to have an endocardial cushion defect with a patched ventricular septal defect and an atrial septal defect of the ostium primum type. We did not observe any untoward effects due to the combination of drugs and congenital abnormalities that could be explained on an individual basis. Nifedipine overdose associated with alcohol intoxication, to our knowledge, has not been previously reported.

An experience in designing patient education materials

This article describes the authors' experience in designing four booklets for patient education. Design considerations, readability estimates, layout preparation, content validity, and printing considerations are discussed.

Presence and actions of vasopressin-like peptides in the rabbit anterior uvea

The presence of vasopressin-like immunoreactivity (VP-IR) in the rabbit eye was demonstrated by radioimmunoassay. Trigeminal nerve denervation resulted in a significant and selective decrease in the levels of VP-IR in the iris sphincter muscle and the cornea. The isolated iris sphincter muscle contracted in response to low concentrations of [Arg8]vasopressin (AVP) and related peptides. The V1 vasopressin receptor antagonist, d(CH2)5Tyr(Me)AVP, potently inhibited the contractile responses to AVP. AVP was found to induce an increase in the accumulation of inositol phosphates in the iris sphincter muscle but not in the dilator/ciliary body preparation in vitro. The present investigation demonstrates the presence of VP-IR in the rabbit eye and that this substance may be another sensory nerve-derived mediator acting on specific target sites in the anterior uvea.

Osmotic regulation of hypothalamo-neurointermediate lobe corticotrophin-releasing factor-41 in the rat

We have detected significant amounts of corticotrophin-releasing factor-41 (CRF-41) in the rat hypothalamo-neurointermediate lobe system using a radioimmunoassay and reversed-phase high-performance liquid chromatography. Total amounts of CRF-41 in extracts of median eminence (ME), supraoptic nucleus (SON), paraventricular nucleus (PVN) and neurointermediate lobe (NIL) from control animals were 1076 +/- 132, 196 +/- 44, 22 +/- 7 and 147 +/- 50 fmol respectively (means +/- S.E.M., n = 6). In animals given 340 mmol NaCl/l instead of tap water to drink for 12 days, no significant changes occurred in the CRF-41 content of the ME, SON or PVN, but CRF-41 content increased more than twofold in the NIL (362 +/- 58 fmol). Plasma concentrations of CRF-41 and ACTH in control animals were 23 +/- 6 and 51 +/- 8 pmol/l respectively. After saline treatment no significant change in plasma CRF-41 was detected (20 +/- 8 pmol/l) but concentrations of circulating ACTH were decreased (15 +/- 2 pmol/l). The CRF-41 content of both the ME and the NIL was significantly depleted after intracerebroventricular injection of colchicine (414 +/- 81 and 34 +/- 7 fmol respectively). These data suggest that NIL CRF-41 is of hypothalamic origin and can be regulated by an osmotic stimulus.

Differential effects of hypothalamic catecholamine depletion on the release of arginine vasopressin and CRF-41 into hypothalamo-hypophyseal portal blood

The effects of 6-hydroxydopamine lesions of the ventral noradrenergic bundle (VNAB) and of intracerebroventricular 6-hydroxydopamine on hypothalamo-hypophyseal portal blood (HPB) concentrations of arginine vasopressin (AVP), corticotrophin releasing factor (CRF-41), and noradrenaline have been investigated. VNAB lesions and intracerebroventricular 6-hydroxydopamine caused a reduction of HPB CRF-41 concentration, while AVP remained unchanged. HPB noradrenaline concentration was reduced in animals treated with lateral ventricular 6-hydroxydopamine, but was unchanged in VNAB lesioned animals. Our results suggest differential effects of noradrenaline on the release of AVP and CRF-41 into HPB.

Immunoreactive vasopressin and oxytocin in hypothalamo-hypophysial portal blood of the Brattleboro and Long-Evans rat: effect of adrenalectomy and dexamethasone

Immunoreactive vasopressin and oxytocin were measured in the hypothalamo-hypophysial portal blood of both Long-Evans and homozygous Brattleboro rats. Adrenalectomy caused an increase in vasopressin immunoreactivity in portal blood in the Long-Evans strain, whilst administration of dexamethasone to these adrenalectomized animals resulted in a reduction in portal vasopressin immunoreactivity to levels below those seen in sham-operated animals. This vasopressin immunoreactivity co-eluted with synthetic vasopressin on high-pressure liquid chromatography (HPLC), and diluted in parallel in radio-immunoassay. In Brattleboro rats, however, although vasopressin-like immunoreactivity was detected, the portal concentration did not vary with the adrenal status of the animal, nor did it show the characteristics of standard vasopressin on HPLC or in immunoassay. Oxytocin was present in the portal blood of both Long-Evans and Brattleboro rats at similar very high concentrations, but did not vary in response to adrenalectomy. These results are consistent with a role for vasopressin, but not oxytocin, in the hypothalamic response to adrenalectomy and glucocorticoid feedback. Neither vasopressin immunoreactivity nor oxytocin appear to subserve this role in the homozygous Brattleboro rat.

Oxytocin in the central nervous system and sexual behaviour in male rats

Concentrations of oxytocin (OT) and vasopressin (AVP) were measured in cerebrospinal fluid (CSF) obtained from the cisterna magna of freely moving rats. Basal levels of OT and AVP were approximately 9 fmol/ml in both male and female. In the male rats this increased to approximately 18 fmol/ml 5 min after ejaculation, and 27 fmol/ml 20 min after ejaculation. No increase from basal levels occurred when males were placed with unreceptive females, or alone in the test environment. AVP levels were unchanged in any condition. Preliminary investigations indicate that discrete electrolytic lesions to the lateral and posterior parvocellular hypothalamic paraventricular nucleus (PVN) abolished this ejaculation-associated increase in CSF OT, prolonged mount and intromission latencies and reduced the absolute postejaculatory interval (PEI). We conclude that intracerebrally projecting OT systems may be activated during coitus and may contribute to the mechanisms underlying postejaculatory refractoriness.

Vasopressin activation of phosphatidylinositol metabolism in rat anterior pituitary in vitro and its modification by changes in the hypothalamo-pituitary-adrenal axis

The ability of vasopressin to stimulate the accumulation of 3H-labelled inositol phosphates was studied in vitro using prelabelled rat anterior pituitary quarters. [8-Arginine] vasopressin activates inositol lipid breakdown in this system in a time- and dose-dependent manner; vasopressin (3 X 10(-7) M) resulted in a 1.8-fold stimulation of inositol phosphate accumulation over control accumulation after 10 min. This response to vasopressin is inhibited by the specific V1 antagonist (CH2)5Tyr(Me)AVP. Both oxytocin and the selective V2 agonist DDAVP also show some agonist activity, but are considerably less potent than arginine vasopressin. Corticotrophin-releasing factor alone had no effect on inositol phosphate production, whilst a high dose given in conjunction with vasopressin resulted in a diminution of the response below that found with the same concentration of vasopressin alone. Anterior pituitaries from vasopressin-deficient Brattleboro rats also show a phosphatidylinositol response to vasopressin. Pituitaries from rats that had been adrenalectomized 4 days earlier showed no increase in inositol phosphate accumulation in response to vasopressin. Daily administration of dexamethasone (40 micrograms/day) reversed this effect of adrenalectomy. This reversal was not seen when dexamethasone (40 micrograms/ml) was added to the incubation medium of adrenalectomized rat pituitary quarters. These results confirm that the rat anterior pituitary contains functional vasopressin receptors capable of activating inositol phospholipid metabolism and that this biochemical response is modified by changes in the hypothalamo-pituitary-adrenal axis.

Oxytocin release during coitus in male and female rabbits: effect of opiate receptor blockade with naloxone

Blood was collected from freely moving rabbits pretreated with saline or naloxone both before and after coitus. In the males, ejaculation was associated with a marked increase in plasma oxytocin concentrations. In the females, oxytocin release was an all-or-nothing phenomenon-either there was no change in oxytocin or it rose to levels very similar to that found post-ejaculation in the males. Naloxone did not alter the proportion of occasions in which females showed an oxytocin response, nor did it have a significant effect on the levels of oxytocin achieved during coitus in either the male or the female rabbits.

Oxytocin and sexual behaviour in the male rat and rabbit

In male New Zealand white rabbits, it was shown that oxytocin but not vasopressin concentrations in plasma were markedly raised after ejaculation. In male Wistar rats, oxytocin infused into the internal carotid artery reduced the number of intromissions made before ejaculation but had no other significant effect. Infusion of oxytocin into the third ventricle increased the latencies to the first mount and intromission and lengthened post-ejaculatory refractory periods. It is suggested that oxytocin released into the periphery during coitus, while not essentially involved in ejaculation, may exert effects on the genital periphery. Behavioural effects of centrally administered oxytocin suggest that it may play a role in the neural mechanisms underlying post-ejaculatory refractoriness.

Ascending brain-stem noradrenergic pathways modulate the renin response to haemorrhage

Ventral noradrenergic projections (VNAB) from lateral tegmental (A1, A2) and dorsal noradrenergic projections (DNAB) from the coeruleal (A6) as well as A1 cell groups in the brain-stem of the rat were lesioned by intracerebral injection of 6-hydroxydopamine. A marked increase in plasma renin activity and adrenaline concentrations followed haemorrhage (0.5 ml/100 g body weight) in the sham-operated rats. VNAB-lesioned rats showed a similar response to the sham-operated controls, but in DNAB-lesioned animals the rise of plasma renin was markedly attenuated.

A vasopressin-like peptide in the mammalian sympathetic nervous system

Vasopressin was among the first mammalian hormonal peptides to be identified and to have its structure determined. Its only undisputed physiological role is as a circulating neurohypophyseal antidiuretic hormone. Other notable effects of vasopressin on peripheral tissues include contraction of vascular smooth muscle, leading to elevation of blood pressure, and activation of glycogenolysis in liver. It has long been clear that vascular smooth muscle and hepatocytes are relatively insensitive to the low concentrations of vasopressin normally present in the circulation, and the physiological significance of their responses has therefore been in doubt. We now report that a new bioactive and immunoreactive vasopressin-like peptide (VLP) is widely distributed in the sympathetic nervous system of mammals, both in the principal noradrenergic neurones of ganglia and in nerve fibres innervating peripheral tissues. In addition to other peptides described in the mammalian sympathetic nervous system, VLP must be considered as a possible mediator of the non-adrenergic responses to sympathetic activation. Moreover, many of the effects previously attributed to circulating vasopressin may be neurally evoked.

Localization and actions of cholecystokinin in the rat pituitary neurointermediate lobe

Rat pituitary neural lobe contained high concentrations of cholecystokinin-like immunoreactivity (CCK-LI). Section of the pituitary stalk resulted in loss of CCK-LI, and both lactation and replacement of drinking water with 2% saline resulted in marked depletion of CCK-LI. Rats with congenital diabetes insipidus (Brattleboro strain) had a 73% reduction in CCK-LI below the levels of hooded Long-Evans controls, where as levels in the brain were unchanged. Release of CCK-LI, labeled dopamine, and gamma-amino butyric acid in response to potassium depolarization was studied. There was a low fractional release of CCK-LI. Addition of sulfated CCK-8 (CCK-8s) to the medium enhanced the calcium-dependent potassium-stimulated release of dopamine, but basal release was unaffected. gamma-Amino butyric acid release was only poorly calcium dependent and not effected by extracellular CCK-8s. Vasopressin and oxytocin release were stimulated by electrical stimulation of the pituitary stalk, and were unaffected by the addition of CCK-8s to the medium. In vivo, however, the injection of 5 micrograms CCK-8s into the third ventricle resulted in increased plasma vasopressin concentrations.

Ascending noradrenergic projections from the brainstem: evidence for a major role in the regulation of blood pressure and vasopressin secretion

The role of projections from the lateral tegmental (A1, A2) and coeruleal (A6) noradrenergic cell groups in the control of arginine vasopressin (AVP) secretion was studied following lesions to the ventral (VNAB) and dorsal (DNAB) noradrenergic bundles by 6-hydroxydopamine. These lesions were associated with the expected, large reductions in cortical (DNAB) and hypothalamic (VNAB) noradrenaline concentrations. Vehicle injected, control animals and VNAB lesioned animals showed a similar AVP secretory response to haemorrhage, whilst the DNAB group showed a markedly diminished release of AVP in response to this challenge. Following Clonidine injection, both controls and VNAB animals showed major reductions in plasma AVP concentrations, but again the DNAB group behaved in a different manner, with a marked attenuation of the inhibitory effect of Clonidine on AVP secretion. In addition, the DNAB group had a significantly lower basal blood pressure, a greater initial agonist response to Clonidine and a loss of the hypotensive response to Clonidine in comparison to sham and VNAB lesioned groups. All three groups showed a similar AVP response to intravenous nicotine. These data suggest that noradrenergic projections originating in the locus coeruleus, or in the lateral tegmental NA groups but which ascend together with coeruleal axons in the DNAB, modulate the vasopressin response to visceral stimuli and to Clonidine, and that they also play an important role in mediating the hypotensive effect of Clonidine.

Role for lateral tegmental noradrenergic neurons in the vasopressin response to hypertonic saline

Lesions to the dorsal and ventral noradrenergic pathways were achieved by injecting 6-hydroxydopamine in the periaqueductal midbrain or lateral pons, respectively. Four to 6 weeks after surgery the rats were anaesthetized with pentobarbitone, and hypertonic saline was administered into the peritoneum. Rats with lesions of the ventral noradrenergic pathways showed a significant reduction in the saline-induced rise in plasma vasopressin concentrations, while lesions to the dorsal pathway or control injections were without effect.

Hypothalamic integration of dopaminergic and opiate pathways controlling vasopressin secretion

Lesions of the circumventricular organs were produced by administration of monosodium-L-glutamate to neonatal rats. At 16 weeks of age these rats were given different stimuli to vasopressin release. In control rats, morphine (50 micrograms) injected into the third ventricle resulted in a rapid increase in plasma vasopressin concentrations at 10 min, followed by a reduction at 20 min. The circumventricular organ-lesioned rats, however, showed a pronounced fall in vasopressin secretion both at 10 and 20 min after 50 micrograms morphine. A similar abolition of the morphine-elicited rise in plasma vasopressin could also be achieved by the iv infusion of small doses of dopamine in normal rats. Hypoxic stimuli, which result in a marked rise in vasopressin in normal rats, failed to elicit any increase in circumventricular organ-lesioned animals. Vasopressin release after stimulation with 9% saline, however, was augmented in the lesioned animals. These results suggest that circumventricular organs have an important role in controlling neurohypophyseal secretion and that they differentially control different stimuli to vasopressin release via dopaminergic and opiate pathways.

Naloxone increases the nicotine-stimulated rise of vasopressin secretion in man

Intravenous nicotine was administered to a group of six subjects during the concurrent intravenous infusion of either the opiate antagonist naloxone, or of saline. Nicotine stimulated vasopressin secretion in all subjects. Naloxone infusion increased both the plasma vasopressin response to nicotine and the resulting rise in urine osmolality.

The effect of amniography on amniotic fluid L/S ratio

This report provides data indicating that the water-soluble dye combination commonly used in amniography raises the amniotic fluid lecithin/sphingomyelin ratio.