It has been proposed previously that the metabolic defect in pseudohypoparathyroidism which accounts for parathyroid hormone unresponsiveness is an absence or abnormal form of adenyl cyclase system kidney and presumably bone. To determine whether there associated response mechanism to cyclic adenosine 3′,5′-monophosphate (cyclic AMP), effects extract (PTE), dibutyryl AMP were compared patients with either surgical hypoparathyroidism pseudohypoparathyroidism. PTE both increased serum urinary...

Abstract: Binding of [ 3 H]imipramine in mouse cerebral cortex was found to be nonhomogeneous. Competition experiments, Scatchard analysis and Hill plots are compatible with the existence binding high (nanomo‐lar) low (micromolar) affinity. Low‐affinity could eliminated by use concentrations imipramine as competing ligand. In contrast high‐affinity binding, low‐affinity unrelated neuronal uptake system for serotonin.

The biphasic nature of the lipolytic dose-response curve epinephrine in fat cells from young rats (40-45 days) was confirmed. first phase (Lipolysis I) occurred at concentrations 10-7 M to 3 X 10-6 M. second 11) low6 Insulin (0.1 mU/ml) abolished Lipolysis I and slightly augmented 11. Higher insulin (1.0 I1 even further. These results may help explain some conflicting re- ports literature concerning effects on lipolysis. using old (14-16 months) monophasic. Based with propranolol, Kt-free...

Using the flask-incubated fat cell system, alterations in glycerol release (lipolysis) and cAMP accumulation were determined after incubation with isoproterenol or forskolin. These agents caused concentration-dependent increases both lipolysis. The maximum responses to forskolin for each variable greater than corresponding isoproterenol. increased by presence of either adenosine deaminase theophylline. Under these conditions, high concentrations continued increase while having no further...

Acetylcholine (ACh) produced a time and dose-dependent increase in cyclic 3',5'-guanosine monophosphate (cyclic GMP) levels perfused rat hearts without any significant (P greater than .05) change 3',5'-adensoine AMP) level or glycogen phosphorylase activity. Epinephrine both cyclin AMP activity but no GMP levels. When ACh (10(-6) M) was infused into during the infusion of epinephrine M), time-dependent decrease occurred, which preceded less In epinephrine-stimulated hearts, Similar...

The effects, in vivo, of epinephrine, glucagon, and dibutyryl cyclic adenosine 3′,5′-monophosphate (cyclic AMP) on the glycogen content rat heart liver and, vitro, upon adenylate cyclase activity homogenates were determined during latter third gestation neonatal period. Hepatic was depleted by 3′,5′-monophosphate, but myocardial only epinephrine AMP neonates. augmented both (10-5 M) glucagon M), increased tissue obtained from 16, 18, 20 day fetal rats. Myocardial responsiveness to present...

Abstract In vitro methods currently utilized for the determination of lipolytic responses in adipose tissue have not allowed continuous monitoring rapid successive changes rates lipolysis. The perifused fat cell system this investigation offers a simple, reproducible method by which minute-to-minute rate lipolysis isolated cells may be monitored. technique, are placed plastic column and with albumin-containing buffer absence presence various agents. Using we been able to observe alterations...

Isolated fat cells prepared from the epididymal pads of adrenalectomized rats exhibited a reduced lipolytic response to epinephrine. Reduced responsiveness was first observed at 3 hr and maximal 24 following surgery. Plasma levels corticosterone had fallen near zero by hr. The responses ACTH, dibutyryl cyclic AMP theophylline were also reduced. Maximum rates produced combination epinephrine not altered. Loss could be prevented subcutaneous injection hydrocortisone. Basal,...

By using perfused fat cells the effect of isoproterenol on adenosine 3':5'-monophosphate (cAMP) levels, cAMP-dependent protein kinase activity and lipolysis was studied. An infusion (10(-7) M) resulted in a time-dependent increase cAMP levels cells. Both parameters reached maximum values after 5 min drug infusion, then declined to steady-state by 10 min. At 60 min, were still significantly (P less than .05) elevated over basal. Dose-response curves determined for glycerol release. All three...

Previous studies of the ability immature heart to respond glucagon have yielded conflicting results. To test possibility that apparent discrepancies might be explained in part by species variability, isolated hearts fetal mice and rats (13-22 days' gestational age) were studied under identical conditions vitro. Changes atrial rate ventricular contractility measured spontaneously beating exposed glucagon, activation adenylate cyclase was assayed cardiac homogenates. In 16 age or less, there...

Abstract The role of Ca2+ in adrenocorticotropic hormone (ACTH)-stimulated lipolysis rat adipocytes was investigated using perifused fat cells. With this system, it is possible to monitor minute-to-minute changes glycerol release from during both the activation and inactivation phases hormone-induced lipolysis. lipolytic response ACTH dose-dependent 0.1 unit per ml produced maximal response. Unlike observed with other polypeptide hormones catecholamines, cessation infusion did not result a...

The cyclic form of somatotropin release inhibitor factor over a concentration range from 0.50 to 8.0 μg/ml was found inhibit glucagon-stimulated AMP accumulation in isolated rat hepato-cytes.

The relationships between cyclic AMP (cAMP) levels and glycerol release (lipolysis) were determined for isoproterenol forskolin under varied conditions in the isolated fat cell of rat. Prevention inhibitory action endogenous adenosine [by deaminase (100 mU/ml) or theophylline (3.3 X 10(-4) M)] resulted increased cAMP rates lipolysis with forskolin. However, relationship remained same all conditions. N6-phenylisopropyladenosine (PIA; an analog adenosine) abolished increase level produced by...

Papaverine, 1-ethyl-4-(isopropylidenehydrazine)-1H-pyrazole-(3,4-b)-pyridine-5-carboxylic acid, ethylester-HCl (SQ 20,009) and theophylline were compared as phosphodiesterase inhibitors at two different substrate concentrations of cyclic 39 , 59-adenosine monophosphate (cyclic AMP). At both AMP, papaverine SQ 20,009 found to be more potent than theophylline. However, only was capable stimulating lipolysis in the isolated fat cell preparation. All three compounds augmented lipolytic response...