Dopamine and 5-hydroxytryptamine actions on the cardiac ganglion of the lobster Homarus americanus

Berlind, Allan

doi:10.1007/s003590050186

Cited by 18 publications

(12 citation statements)

References 25 publications

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“…Serotonin increases the heartbeat of intact animals even after the cardioregulatory nerves are severed (Guirguis and Wilkens, 1995), suggesting that serotonin acts directly on the cardiac ganglion. This was subsequently verified by Berlind's observation that serotonin increases and prolongs the bursting output of the cardiac ganglion in vitro (Berlind, 1998). Such effects would be consistent with serotonin increasing heartbeat frequency and contraction amplitude.…”

Section: Serotonergic Modulation Of Heart Rate and Contractionmentioning

confidence: 55%

Temperature dependence of cardiac performance in the lobsterHomarus americanus

Worden

Clark

Conaway

et al. 2006

Journal of Experimental Biology

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SUMMARY The lobster Homarus americanus inhabits ocean waters that vary in temperature over a 25°C range, depending on the season and water depth. To investigate whether the lobster heart functions effectively over a wide range of temperatures we examine the temperature dependence of cardiac performance of isolated lobster hearts in vitro. In addition, we examined whether modulation of the heart by serotonin depends on temperature. The strength of the heartbeat strongly depends on temperature, as isolated hearts are warmed from 2 to 22°C the contraction amplitude decreases by greater than 60%. The rates of contraction and relaxation of the heart are most strongly temperature dependent in the range from 2 to 4°C but become temperature independent at warmer temperatures. Heart rates increase as a function of temperature both in isolated hearts and in intact animals, however hearts in intact animals beat faster in the temperature range of 12–20°C. Interestingly, acute Q10 values for heart rate are similar in vivo and in vitro over most of the temperature range, suggesting that temperature dependence of heart rate arises mainly from the temperature effects on the cardiac ganglion. In contrast to earlier reports suggesting that the strength and the frequency of the lobster heartbeat are positively correlated, we observe no consistent relationship between these parameters as they change as a function of temperature. Stroke volume decreases as a function of temperature. However, the opposing temperature-dependent increase in heart rate partially compensates to produce a relationship between cardiac output and temperature in which cardiac output is maximal at 10°C and significantly decreases above 20°C. Serotonin potentiates contraction amplitude and heart rate in a temperature-independent manner. Overall, our results show that although the parameters underlying cardiac performance show different patterns of temperature dependence, cardiac output remains relatively constant over most of the wide range of environmental temperatures the lobster inhabits in the wild.

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Section: Serotonergic Modulation Of Heart Rate and Contractionmentioning

confidence: 55%

Temperature dependence of cardiac performance in the lobsterHomarus americanus

Worden

Clark

Conaway

et al. 2006

Journal of Experimental Biology

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“…A single central effect of dopamine on frequency thus appears to be the most parsimonious explanation. In previous studies using ligatures and Vaseline wells, dopamine was found to affect ganglionic burst frequency most strongly when applied to the posterior region of the CG ; see also Berlind 1998Berlind , 2001a. We propose therefore that the effect on frequency is achieved primarily by dopamine release from the projections of the L-cell that terminate in the area of the small interneurons (thin solid arrows in Fig.…”

Section: Cardioactive Actions Of Dopaminementioning

confidence: 64%

“…Because dopamine also produces increases in burst frequency, burst duration, and the number of impulses per burst in isolated cardiac ganglia (Berlind 1998;Miller et al 1984), it is easy to assume that all of the effects observed in the cardiac system are a simple consequence of its central actions. However, when the actions of dopamine are quantitatively compared on the CG with and without the peripheral cardiac musculature, as we have done here, it becomes clear that matters are likely to be considerably more complex.…”

Section: Cardioactive Actions Of Dopaminementioning

confidence: 99%

Modulation of an Integrated Central Pattern Generator–Effector System: Dopaminergic Regulation of Cardiac Activity in the Blue CrabCallinectes sapidus

Fort

Březina²,

Miller³

2004

Journal of Neurophysiology

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Fort, Timothy J., Vladimir Brezina, and Mark W. Miller. Modulation of an integrated central pattern generator-effector system: dopaminergic regulation of cardiac activity in the blue crab Callinectes sapidus. J Neurophysiol 92: 3455-3470, 2004; doi:10.1152/ jn.00550.2004. Theoretical studies have suggested that the output of a central pattern generator (CPG) must be matched to the properties of its peripheral effector system to ensure production of functional behavior. One way that such matching could be achieved is through coordinated central and peripheral modulation. In this study, morphological and physiological methods were used to examine the sources and actions of dopaminergic modulation in the cardiac system of the blue crab, Callinectes sapidus. Immunohistochemical localization of tyrosine hydroxylase (TH) revealed a prominent neuron in the commissural ganglion, the L-cell, that projected a large-diameter axon to the pericardial organ (PO) by an indirect and circuitous route. Within the PO, the L-cell axon gave rise to fine varicose fibers, suggesting that it releases dopamine in a neurohormonal fashion onto the heart musculature. In addition, one branch of the axon continued beyond the PO to the heart, where it innervated the anterior motor neurons and the posterior pacemaker region of the cardiac ganglion (CG). In physiological experiments, exogenous dopamine produced multiple effects on contraction and motor neuron burst parameters that corresponded to the dual central-peripheral modulation suggested by the L-cell morphology. Interestingly, parameters of the ganglionic motor output were modulated differently in the isolated CG and in a novel semiintact system where the CG remained embedded within the heart musculature. These observations suggest a critical role of feedback from the periphery to the CG and underscore the requirement for integration of peripheral (neurohormonal) actions and direct ganglionic modulation in the regulation of this exceptionally simple system.

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“…In crustaceans, short-term control over cardiac performance is provided by excitatory and inhibitory nerves that modulate heart rate and contractility for periods of up to several seconds (Florey, 1960;Field and Larimer, 1975). Longer-term excitation is provided by a variety of circulating hormones that increase the rate and strength of the heartbeat for periods lasting from minutes to hours (Cooke and Hartline, 1975;Benson, 1984;Miller et al, 1984;Sullivan and Miller, 1984;Worden et al, 1995;Berlind, 1998). This raises the question of whether crustaceans might also employ long-term inhibitory mechanisms to counteract these long-lasting excitatory mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Nitric Oxide Inhibits the Rate and Strength of Cardiac Contractions in the LobsterHomarus americanusby Acting on the Cardiac Ganglion

et al. 2004

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The lobster heart is synaptically driven by the cardiac ganglion, a spontaneously bursting neural network residing within the cardiac lumen. Here, we present evidence that nitric oxide (NO) plays an inhibitory role in lobster cardiac physiology. (1) NO decreases heartbeat frequency and amplitude. Decreased frequency is a direct consequence of a decreased ganglionic burst rate. Decreased amplitude is an indirect consequence of decreased burst frequency, attributable to the highly facilitating nature of the synapses between cardiac ganglion neurons and muscle fibers (although, during prolonged exposure to NO, amplitude recovers to the original level by a frequencyindependent adaptation mechanism). NO does not alter burst duration, spikes per burst, heart muscle contractility, or amplitudes of synaptic potentials evoked by stimulating postganglionic motor nerves. Thus, NO acts on the ganglion, but not on heart muscle. (2) Two observations suggest that NO is produced within the lobster heart. First, immunoblot analysis shows that nitric oxide synthase (NOS) is strongly expressed in heart muscle relative to other muscles. Second, L-nitroarginine (L-NA), an NOS inhibitor, increases the rate of the heartbeat (opposite to the effects of NO). In contrast, the isolated ganglion is insensitive to L-NA, suggesting that heart muscle (but not the ganglion) produces endogenous NO. Basal heart rate varies from animal to animal, and L-NA has the greatest effect on the slowest hearts, presumably because these hearts are producing the most NO. Thus, because the musculature is a site of NOS expression, whereas the ganglion is the only intracardiac target of NO, we hypothesize that NO serves as an inhibitory retrograde transmitter.

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Dopamine and 5-hydroxytryptamine actions on the cardiac ganglion of the lobster Homarus americanus

Cited by 18 publications

References 25 publications

Temperature dependence of cardiac performance in the lobsterHomarus americanus

Temperature dependence of cardiac performance in the lobsterHomarus americanus

Modulation of an Integrated Central Pattern Generator–Effector System: Dopaminergic Regulation of Cardiac Activity in the Blue CrabCallinectes sapidus

Nitric Oxide Inhibits the Rate and Strength of Cardiac Contractions in the LobsterHomarus americanusby Acting on the Cardiac Ganglion

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