Dopamine D1 stimulation of Na+,K+,Cl- cotransport in human NPE cells: effects of multiple hormones.

PURPOSE: To determine the effects of dopamine on Na+,K+,Cl- cotransport in human ciliary nonpigmented epithelial (NPE) cells. METHODS: The authors used 86Rb+ as a marker for K+ to study ouabain-insensitive, bumetanide-sensitive 86Rb+ uptake in cultured fetal human NPE monolayers. RESULTS: Na+,K+,Cl- cotransport was stimulated 1.63-fold by 10 microM dopamine. Stimulation was dose dependent, with a maximum stimulation occurring at 10 microM dopamine and an EC50 of 0.5 microM. NaK-ATPase (measured as ouabain-sensitive, bumetanide-insensitive 86Rb+ uptake) and bumetanide-insensitive, ouabain-insensitive 86Rb+ uptake were not affected by dopamine. The D1-receptor-specific antagonist, SCH23390, inhibited stimulation by 10 microM dopamine more than 90% at 1 microM, with an IC50 of 4 nM, whereas the D2-receptor-specific antagonist, sulpiride, was over 250 times less effective. Similarly, a D1 agonist, SKF81297, was more potent than the D2 agonist bromocriptine in stimulation of Na+,K+,Cl- cotransport. The beta-adrenergic antagonists timolol and propranolol did not significantly inhibit stimulation of Na+,K+,Cl- cotransport by dopamine. Conversely, SCH23390, showed minimal inhibition of isoproterenol stimulation of Na+,K+,Cl- cotransport. Stimulation by maximally stimulating concentrations of isoproterenol and dopamine were not additive, but were similar to stimulation by 1 microM forskolin, suggesting that adenylyl cyclase may be close to maximally activated by either catecholamine. In vivo concentrations (stimulation approximately 25% over control) of dopamine, isoproterenol, and norepinephrine added together stimulated Na+,K+,Cl- cotransport 80% to 89% of stimulation by maximal concentrations of these drugs. The protein kinase A inhibitor N-[2-p-bromocinnamylaminoethyl]-5-isoquinolinesulfonamide (H-89) blocked dopamine stimulation of Na+,K+,Cl- cotransport by more than 75%, whereas phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, given with 10 microM dopamine inhibited Na+,K+,Cl- cotransport by 75% to 80%, similarly to inhibition by PMA given alone. CONCLUSIONS: Dopamine stimulates Na+,K+,Cl- cotransport in NPE through dopamine-D1-type receptors and activation of protein kinase A. Beta-adrenergic receptors do not appear to play a role. Inhibition of Na+,K+,Cl- cotransport by protein kinase C is dominant over stimulation of Na+,K+,Cl- cotransport through the cyclic adenosine monophosphate pathway.

Technetium-99m-pertechnetate uptake by intrathyroidal parathyroid adenoma.

A 57-yr-old woman was referred for preoperative scintigraphic localization of a parathyroid adenoma. Double-phase 99mTc-sestamibi imaging was performed followed by a separate-day [99mTc]pertechnetate thyroid scan. There was marked accumulation of both tracers by a right lower pole ¿thyroid' nodule which, at surgery, proved to be an intrathyroidal parathyroid adenoma. Hypervascularity is the presumed explanation for rare cases of pertechnetate-avid parathyroid adenomas.

Beta-adrenergic stimulation of Na+, K+, Cl- cotransport in fetal nonpigmented ciliary epithelial cells.

PURPOSE: The effects of adrenergic agonists and antagonists on Na+, K+, Cl- cotransport in fetal human nonpigmented ciliary epithelial (NPE) cells were investigated. METHODS: 86Rb+ as a marker for K+ was used to study ouabain-insensitive, bumetanide-sensitive 86Rb+ uptake in cultured NPE monolayers. Cyclic adenosine monophosphate (cAMP) formation in NPE cells was determined by radioimmunoassay. RESULTS: 1 microM isoproterenol caused a 1.65-fold stimulation in Na+,K+,Cl cotransport measured as bumetanide-sensitive, ouabain-insensitive 86Rb+ uptake. The half-maximal concentration for this effect was 6.4 nM, with maximal stimulation at 100 nM isoproterenol. Epinephrine stimulated Na+, K+, Cl- cotransport similarly to isoproterenol, whereas norepinephrine stimulated at much higher concentrations (half-maximal effective concentration = 1.4 microM). Stimulation of Na+, K+, Cl- cotransport by 1 microM isoproterenol was inhibited completely by the beta 2-adrenergic antagonist ICI-118,551 at 100 nM, with a half-maximal inhibitory concentration of 5 nM. Neither atenolol, a beta 1-specific adrenergic antagonist, prazosin, an alpha 1-adrenergic antagonist, nor yohimbine, an alpha 2-specific antagonist, was as effective. These four antagonists inhibited isoproterenol-stimulated cAMP formation with potencies similar to those observed against stimulated Na+, K+, Cl- cotransport. The hypotensive adrenergic antagonist timolol, propranolol, and betaxolol also inhibited Na+, K+, Cl- cotransport stimulated by isoproterenol in the order timolol > propranolol > betaxolol. Na+, K+, Cl- cotransport could be maintained in a stimulated state for at least 2 hours in the presence of agonist, but activity returned to basal levels within 20 minutes of isoproterenol removal. Adrenergic stimulation of Na+, K+, Cl- cotransport was blocked 80% to 85% by 70 microM H-89, a protein kinase A inhibitor. CONCLUSIONS: These data suggest that beta 2-adrenergic receptor activation results in increased cAMP formation and sustained stimulation of Na+, K+, Cl- cotransport in fetal human NPE cells. Protein kinase A activation is required for maximal stimulation of Na+, K+, Cl- cotransport by adrenergic agonists.

Parathyroid adenomas without sestamibi retention.

The authors describe two patients in whom parathyroid adenomas were successfully localized with a Tc-99m sestamibi/pertechnetate subtraction technique, but who did not exhibit differential sestamibi retention on delayed imaging. Although the frequency of this occurrence is unclear, it suggests that some parathyroid adenomas will be missed if reliance is placed on sestamibi retention alone without simultaneous thyroid imaging.

Reflux after esophagectomy and interposition of right colon.

OBJECTIVE: To determine the nature of reflux after esophagectomy and interposition of right colon. DESIGN: A case series. SETTING: A university hospital. PATIENTS: Five patients (mean age 43 years) in whom right colon had been interposed after total esophagectomy. INTERVENTIONS: Endoscopy and biopsy, manometry, 24-hour ambulatory pH testing. MAIN OUTCOME MEASURES: Endoscopic and histologic appearances of the colon, type of motor activity in the grafted colon and the type of reflux. RESULTS: In all patients the grafted colon was macroscopically and microscopically normal. There was nonperistaltic motor activity in the interposed colon in two patients. All patients had an abnormal pattern of alkaline reflux, and one patient had abnormal acid reflux. CONCLUSIONS: The clinical effect of alkaline reflux in patients with colonic interposition after total esophagectomy may be slight. Histologic and gross changes are likely to be minimal.

Eye movements of stutterers.

As a consequence of recent inquiries into the brainstem activity of stutterers, saccades and pursuit were evaluated in stutterers and their matched normals while silent and talking. No ocular motor instabilities or aberrations caused by speech were found. Saccadic latencies and gains for the stutterers were normal, but peak velocities were higher and durations were shorter. This finding is consistent with hypotheses of speech dysfluency proposed by others. The gains of these fast saccades were kept normal by an adaptive decrease in the duration of the neural pulse producing the saccade. It is proposed that these fast saccades are a result of increased excitatory input to the burst cells in the brainstem.

Enzyme activities and protein concentration in the intraocular fluids of ten mammals.

An attempt was made to establish normal values for the total protein concentrations and the enzyme activities of LDH, MDH and PGI in the intraocular fluids of rats, guinea pigs, rabbits, cats, dogs, sheep, cattle, pigs, horses and humans. Remarkably little species differences were noted in 9 of the 10 mammals with vitreal enzyme activities falling into a narrow range between 8.4 U/l (PGI, horse) and 92.4 U/l (MDH, guinea pig). All species obeyed the sequence aqueous less than vitreous less than serum with exception of the rat, where vitreous activities surpassed serum at least two-fold. The very low enzyme activities in the aqueous and vitreous humors demand special precautions against contaminations which can either derive from post-mortem storage or inadequate sampling procedures. Conversely elevated enzyme activities could be used as probes for pathological processes or as a check for a clean preparation.

Characterization of cells of the normal aortic endothelium of adult rats and changes due to endotoxin shock. I. Communication: light microscopy, autoradiography, DNA cytophotometry, and enzyme histochemistry.

Aortic endothelium of normal and endotoxin treated rats was investigated in "Häutchen" preparations by light microscopy, autoradiography, DNA cytophotometry, and enzyme histochemistry. In the endothelium of control rats the following cell populations were found: 1. Endothelial cells (90% of all cells in endothelium), characterized by the alignment of the longitudinal axis of their nuclei, their light microscopic morphology, their DNA content resp. DNA synthesis, and by their enzymatic activity; 2. mononuclear cells (10% of all cells in endothelium), identified as mature blood monocytes, mononuclear phagocytes (macrophages), and as lymphocytes; 3. granulocytes (less than 1% of all cells in endothelium). The presence of mononuclear cells and granulocytes in the normal endothelium appears to be the expression of a physiological repair process in endothelium. After endotoxin application one can observe an endothelial damage and then a repair process. During the repair of endothelium the following processes occurred: An increase of DNA synthesis particularly of endothelial cells, an aggregation of platelets on the endothelial surface, an increase in number of granulocytes and at last an increase in number of activated mononuclear cells. Participation of mononuclear cells in the physiological as well as in the pathological repair process of endothelium was shown by the present investigation. The process of transformation of mononuclear cells into endothelial cells is discussed at the same time.

Acinic cell cancers of the parotid gland in children. Comments based on two affected girls.

Analysis of the literature and our own experiences with two pediatric cases of salivary gland tumors have yielded the following information: 1) under the age of five years, nearly all parotid tumors are mesenchymal in origin; 2) malignant tumors of the parotid during childhood occur much more often in girls than in boys; 3) mucoepidermoid carcinoma is the most common salivary gland malignancy in children; 4) the second next most common is of the undifferentiated variety; 5) acinic cell carcinoma, in general, represent fewer than 3 per cent of all salivary gland tumors, and two-thirds of these occur in females. Lymph node metastasis is rare, recurrence being usually local or blood borne; 6) Acinic cell carcinoma are rare in childhood. They are not highly malignant, yet capable of killing. Local recurrences are frequent. The best primary treatment would appear to be complete surgical excision. Blood borne metastases may develop more than 20 years after initial treatment.