A behavioral analysis of peaking in residential electrical-energy consumers

This study was concerned with "peaking", which is the tendency for electrical-energy users to consume at high rates for brief periods during the day. Peaking results in the inefficient use of generating facilities, which may lead to unfavorable effects on the environment, such as the construction of new energy producing facilities or the activation of older, less safe, generating units. A continuous data collection system to monitor consumption of electrical energy was installed in the homes of three volunteer families. Information, feedback, and incentives were evaluated for their effects on peak energy consumption. A combination of feedback plus incentives was most effective and reduced peaking about 50%. Removal of experimental treatments resulted in a return to pre-treatment patterns of consumption.

In vivo pertussis toxin treatment attenuates some, but not all, adenosine A1 effects in slices of the rat hippocampus

In order to examine the involvement of G-proteins in mediating the different effects of adenosine A1-receptor stimulation in rat hippocampus we injected pertussis toxin (PTX) intraventricularly close to the hippocampus and examined its effect in slices 48-60 h later. The in vivo PTX treatment caused a partial (50 +/- 5%) inhibition of the [32P]ADP ribosylation produced by PTX added together with [32P]NAD in vitro. Such PTX treatment eliminated the electrophysiologically determined gamma-amino-n-butyric acid (GABA)B receptor response in the hippocampal CA1 region, but GABAA effects were unaffected. The adenosine (50 microM)-mediated hyperpolarization and decrease in input resistance as well as the adenosine-mediated inhibition of low calcium-induced bursting in pyramidal CA1 neurons were virtually abolished. The same was true for the decrease in [3H]cyclic AMP accumulation that is produced by the adenosine analogue R-N6-phenylisopropyl adenosine (R-PIA) in forskolin-treated hippocampal slices. As far as modulation of transmitter release was concerned, the R-PIA (1 microM)-induced inhibition of release of both [3H]noradrenaline (NA) and [3H]acetylcholine (ACh) evoked by field stimulation in hippocampal slices was affected hardly or not at all by pertussis toxin treatment. The inhibitory effect of adenosine on field excitatory postsynaptic potential (EPSP)s evoked in the CA1 region was unaltered by PTX pretreatment. The present results show that in vivo pertussis toxin treatment can inhibit some but not all A1-adenosine-receptor effects. This strongly suggests that closely similar A1 receptors might be coupled to G-proteins that differ in their sensitivity to PTX treatment.

Somatic motor axons can innervate autonomic neurones in the frog heart

1. The effects of sympathetic and parasympathetic stimulation on the heart rate in frogs were tested after hearts were reinnervated with a somatic motor nerve. When frogs were vagotomized and hypoglossal axons were redirected to the heart for 8 or more weeks, stimulating the redirected hypoglossus nerve produced a parasympathetic-like inhibition of the heart. Stimulating sympathetic rami of the anastomosed hypoglossus nerve produced cardiac acceleration.2. Individual parasympathetic neurones received synaptic input from hypoglossal terminals. The excitatory post-synaptic potentials evoked by hypoglossal stimulation were much smaller than those evoked by vagal stimulation in control or vagal-reinnervated ganglia. However, hypoglossal axons innervated most (71%) of the ganglion cells and this level of innervation persisted for at least 60 weeks.3. Hypoglossal axons formed networks of varicose terminals within cardiac ganglia and established axo-axonic synapses with parasympathetic neurones. Hypoglossal terminals did not reinnervate the neuronal perikarya, in contrast to vagal axons in control or vagal-reinnervated ganglia.4. Axo-axonic synapses from redirected hypoglossal axons were identified in cardiac ganglia by bathing isolated hearts in horseradish peroxidase (HRP) and stimulating the redirected nerve. Electron micrographs showed that axo-axonic synapses contained HRP-labelled presynaptic vesicles.5. The source of foreign innervation in experimental cardiac ganglia was confirmed to be hypoglossal motoneurones (a), by comparing the conduction velocity of the redirected presynaptic axons (1.32 m/sec) with regenerating vagal preganglionic fibres (< 0.3 m/sec), and (b), by retrograde HRP-labelling of large motoneurones in the hypoglossal nucleus after applying peroxidase to the axons which had grown into the heart.

Competitive elimination of foreign motor innervation on autonomic neurones in the frog heart

1. Somatic motoneurones are capable of forming functional synapses when redirected to vagotomized autonomic neurones in the frog heart. We tested if regenerating vagus nerves could reinnervate ganglion cells in the presence of foreign hypoglossal innervation and, furthermore, whether hypoglossal innervation persisted when vagal axons regenerated to the heart. 2. Simulating the redirected hypoglossus nerve produced a parasympathetic-like cardiac inhibition in the absence of vagal regeneration. However, when the vagus nerve was allowed to regenerate to the heart, vagal cardio-inhibition was restored and hypoglossal inhibition disappeared. 3. Intracellular recordings showed that 71% of the cardiac ganglion cells were innervated by hypoglossal axons before vagal regeneration, but that this value fell to less than 9% over a period of 40 weeks during vagal regeneration. 4. If the vagus nerve was prevented from regenerating to the heart, hypoglossal innervation did not decline, indicating that elimination of the foreign motor innervation was dependent upon vagal reinnervation. 5. Although hypoglossal terminals formed synapses only on the axons of parasympathetic ganglion cells, regenerating vagal fibres re-established synaptic contact both on axons as well as on neuronal perikarya. 6. The data indicate that in the frog parasympathetic cardiac ganglion, extensive synaptic remodelling can take place during reinnervation and that previously established, inappropriate inputs can be functionally eliminated by regeneration of the native nerve supply.

"Hybrid" synapses formed by foreign innervation of parasympathetic neurons: a model for selectivity during competitive reinnervation

Selectivity of synapse formation after nerve regeneration was tested in the parasympathetic cardiac ganglion of frogs (Rana pipiens). First, we tested the ability of somatic motor axons to establish synaptic connections with denervated ganglion cells by implanting the hypoglossus nerve into the vagotomized heart. After several weeks, stimulation of the implanted hypoglossus mediated a parasympathetic-like inhibition of the heart rate, and synaptic responses produced by hypoglossal stimulation were recorded intracellularly in ganglion cells. Light and electron microscopy indicated that implanted hypoglossal nerve terminals contacted parasympathetic ganglion cells only on their axons and not on the cell body (where most vagal synapses are found in control animals). Second, we tested whether regenerating vagal preganglionic axons would complete with foreign (hypoglossal) terminals for innervation of cardiac ganglion cells. We allowed the vagus nerve to regenerate in animals in which the implanted hypoglossus had established functional contacts with the cardiac ganglion. Vagal axons were able to reinnervate the heart and reestablish synaptic connections on the cell bodies of ganglion cells. Furthermore, functional transmission at the foriegn (hypoglossal) terminals disappeared concomitant with vagal reinnervation.