Corrugation of the skull in Paget's disease of bone

Pertussis toxin sensitive endothelin-1 coupling to inositol phosphate formation via a GTP-binding protein: comparison in SHR and WKY cultured aortic smooth muscle cells

The effects of pertussis toxin on endothelin-1 and noradrenaline coupling to inositol phosphate (IP) formation was investigated in cultured aortic smooth muscle cells from 14 week SHR and WKY rats. Endothelin-1 (10(-6) M) stimulated IP formation was decreased in cells from SHR compared to WKY (WKY 1117 +/- 157, SHR 668 +/- 85% of basal). Pre-incubation with pertussis toxin produced a significant and similar reduction in endothelin stimulated IP production in both SHR (54% reduction) and WKY (55%). However, the observed reduction in endothelin-1 stimulated IP accumulation was still apparent in SHR when compared to WKY. Pertussis toxin preincubation followed by removal of extracellular calcium reduced further the endothelin responses by similar amounts in SHR and WKY cells, but SHR stimulated IP formation remained significantly decreased compared to WKY. The extent of pertussis toxin ADP-ribosylation of Gi alpha was similar in both SHR and WKY cells. Endothelin-1 produced a reduction in the extent of ADP-ribosylation of Gi alpha and this was of similar magnitude in both SHR and WKY cell membranes. In contrast, noradrenaline stimulated IP formation was unaffected by pertussis toxin pre-incubation. It was concluded that SHR cells do not appear to have an alteration in endothelin-1 activated, pertussis toxin sensitive G-protein coupling to IP formation or in the dependence of inositol phosphate formation on extracellular calcium.

Cardiac beta-adrenoceptor desensitization after sinoaortic baroreceptors denervation or isoproterenol-pretreatment

The chronotropic reactivity to beta-adrenergic stimulation was studied in isolated perfused hearts from sinoaortic baroreceptors denervated (SAD) rats in the phases of maximal tachycardia (5 h) and normalized heart rate (15 days) or after repeated injection of isoproterenol (1 mg/kg, 3 times daily for 10 days). The threshold doses of isoproterenol needed to cause a significant acceleration of heart rate were significantly higher in acute SAD (1.6 X 10(-7)M), chronic SAD (3.2 X 10(-7)M), and isoproterenol-pretreated (6.4 X 10(-7)M) rats than in control rats (0.8 X 10(-7)M). The maximal increment in basal heart rate was lower in acute (59%) and chronic (48%) SAD rats and in isoproterenol-pretreated rats (26%) than in control rats (78%). These results suggest that the increased efferent sympathetic outflow to the heart induced by SAD causes desensitization of cardiac beta-adrenoceptors and may explain the gradual tachycardia disappearance in this SAD hypertensive rats.

Systemic and regional haemodynamic responses to isoprenaline in conscious renal hypertensive rabbits

1. Using the electromagnetic flow probe and the radioactive microsphere technique, systemic and regional haemodynamic variables were measured in conscious normotensive and hypertensive rabbits. The rabbits were made hypertensive by unilateral nephrectomy combined with cellophane-wrapping of the remaining kidney and systemic and regional haemodynamic effects of isoprenaline infusions (0.5 micrograms.kg-1 .min-1) were compared in the two groups of animals. 2. Isoprenaline evoked increases in heart rate and cardiac index while the total peripheral resistance decreased. In the hypertensive rabbits the effects were similar, except for a significantly more pronounced decrease in blood pressure. 3. Isoprenaline increased the fraction of the cardiac output delivered to the heart, skin and fat, at the expense of the fractions to the brain, stomach, small intestine, pancreas, liver and kidney(s) in both normotensive and hypertensive animals. Local peripheral resistance was decreased, most prominently, in the heart, skin, skeletal muscle and fat. 4. In the normotensive rabbits pretreatment with propranolol (4 mg.kg-1 infused in 1 h) effectively blocked the cardiovascular responses following isoprenaline infusion. 4. Since the systemic and regional haemodynamic effects of isoprenaline were not less (if anything, slightly more) in the hypertensive than in the normotensive rabbits, our results provide no evidence for subsensitivity of beta-adrenoceptors as a contributory factor in the development of hypertension in this model.

Paget's disease

The dentist may recognize Paget's disease before either systemic manifestations on complications occur. Suspicion may arise through routine oral and radiographic examination as pathologic conditions usually occur first in the jaws and skull. As with any disease, early recognition is helpful in treatment and may necessitate alterations in the proposed dental treatment.