Mechanosensitive hyaluronan secretion: stimulus-response curves and role of transcription-translation-translocation in rabbit joints

Fura 2 is one of a recently-introduced family of Ca++ indicators with improved fluorescent properties compared to quin 2 (Grynkiewicz et al 1985). This study has examined the role of [Ca++]i in thrombin-induced dense granule release using prostacyclin-washed human platelets loaded with either thedense granule marker 14C-5HT (5HT) alone or with 5HT together with quin 2 ([quin2]i = 0.8mM) or fura 2 ([fura 2]i 20-30µM). In the presence of ImM extracellular calcium concentration ([Ca++]i) the [Ca++]e in quin 2 and fura 2 loaded platelets was 93±2 (n=10 experiments) and 133±0.3nM (n=12 experiments) respectively. In either quin 2 or fura 2 loaded platelets suspended in the presence of ImM [Ca++]e, thrombin (0.23-23.InM) promoted a rapid (in secs)concentration-dependent elevation of [Ca++]i from basal values to levels l-2µM, together with a parallel release of dense granules almost identical to that obtained with thrombin in non dye loaded platelets. In fura 2 loaded cells, removal of [Ca++]e inhibited the elevation of [Ca++]i induced by a sub-maximal concentration of thrombin (0.77nM) by 43+5% (n=4) but interestingly had no significant effect (p<0.05) on the rise in [Ca++]i elicited by low thrombin doses (0.231nM). Neither did lowering [Ca++]e inhibit the release of 5HT evoked by thrombin ( 0.231-23.InM) from either fura 2 loaded or non dye loaded platelets. In contrast, in quin 2 loaded platelets, removal of [Ca++]e inhibited the thrombin (0.231-23.InM) stimulated rise in [Ca++]i-by 90% and the 5HT release response to either low (0.231nM), sub-maximal (0.77nM) or maximal (23.InM) thrombin by 100% (n=4), 87+2°/o (n=6)and 2+l°/o (n=4) respectively. Fura 2 but not quin 2 loaded cells suspended in ImM [Ca++]e exhibited a Ca++ response to thrombin concentrations >2.31nM which could be separated into a rapid phasic component and a more sustained 'tonic' like component inhibitable by removal of [Ca++]e or by addition of ImM Ni++ . These data suggest the use of fura 2 rather than quin 2 for investigating stimulus response coupling in platelets, particularly when [Ca++]e is less than physiological. We thank the British Heart Foundation and Ciba-Geigy USA for financial support.

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Stimulus-response coupling in the human neutrophil Transmembrane potential and the role of extracellular Na+

Biochimica et Biophysica Acta (BBA) - Biomembranes ◽

10.1016/0005-2736(80)90523-4 ◽

1980 ◽

Vol 601 ◽

pp. 180-194 ◽

Cited By ~ 51

Author(s):

H.M Korchak ◽

Gerald Weissmann

Keyword(s):

Human Neutrophil ◽

Transmembrane Potential ◽

Stimulus Response

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Role of NO in arterial vascular function of intertidal fish (Girella laevifrons) and marine fish (Isacia conceptionis)

Brazilian Journal of Biology ◽

10.1590/1519-6984.22014 ◽

2016 ◽

Vol 76 (2) ◽

pp. 500-505

Author(s):

F. A. Moraga ◽

N. Urriola-Urriola

Keyword(s):

Nitric Oxide ◽

Sodium Nitroprusside ◽

Marine Fish ◽

Vascular Function ◽

Isometric Tension ◽

Mesenteric Arteries ◽

Response Curves ◽

Intertidal Fish ◽

Branchial Arteries

Abstract Previous studies performed in intertidal fish (Girella laevifrons),as well as marine fish (Isacia conceptionis), showed that acetylcholine (ACh) produced contractions mediated by cyclooxygenases that were dependent on the area and potency of contraction in several arterial vessels. Given that the role of nitric oxide is poorly understood in fish, the objective of our study was to evaluate the role of nitric oxide in branchial afferent (ABA), branchial efferent (ABE), dorsal (DA) and mesenteric (MA) arterial vessels from both Girella laevifrons and Isacia conceptionis. We studied afferent and efferent branchial, dorsal and mesenteric arteries that were dissected from 6 juvenile specimens. Isometric tension studies were done using dose response curves (DRC) for Ach (10–13 to 10–3 M) and blockade with L-NAME (10–5 M), and DRC for sodium nitroprusside (SNP, a donor of NO). L-NAME produced an attenuation of the contractile response in the dorsal, afferent and efferent branchial arteries and a potentiation of the contraction in the MA. SNP caused 70% dilation in the mesenteric artery and 40% in the dorsal artery. Our results suggest that Ach promotes precarious dilatation in MA mediated by NO; data that is supported by the use of sodium nitroprusside. In contrast, in the vessels DA, ABA and EBA our results support that the pathway Ach-NO-relaxation is absent in both species.

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Dissociation of Appetitive Overexpectation and Extinction in the Infralimbic Cortex

Cerebral Cortex ◽

10.1093/cercor/bhy248 ◽

2018 ◽

Vol 29 (9) ◽

pp. 3687-3701 ◽

Cited By ~ 2

Author(s):

Belinda P P Lay ◽

Melissa Nicolosi ◽

Alexandra A Usypchuk ◽

Guillem R Esber ◽

Mihaela D Iordanova

Keyword(s):

Behavioral Change ◽

Reward Learning ◽

Behavioral Modification ◽

Test Drug ◽

Infralimbic Cortex ◽

Stimulus Response ◽

Conditioned Responses ◽

Conditioned Responding ◽

Drug Free

Abstract Behavioral change is paramount to adaptive behavior. Two ways to achieve alterations in previously established behavior are extinction and overexpectation. The infralimbic (IL) portion of the medial prefrontal cortex controls the inhibition of previously established aversive behavioral responses in extinction. The role of the IL cortex in behavioral modification in appetitive Pavlovian associations remains poorly understood. Here, we seek to determine if the IL cortex modulates overexpectation and extinction of reward learning. Using overexpectation or extinction to achieve a reduction in behavior, the present findings uncover a dissociable role for the IL cortex in these paradigms. Pharmacologically inactivating the IL cortex left overexpectation intact. In contrast, pre-training manipulations in the IL cortex prior to extinction facilitated the reduction in conditioned responding but led to a disrupted extinction retrieval on test drug-free. Additional studies confirmed that this effect is restricted to the IL and not dependent on the dorsally-located prelimbic cortex. Together, these results show that the IL cortex underlies extinction but not overexpectation-driven reduction in behavior, which may be due to regulating the expression of conditioned responses influenced by stimulus–response associations rather than stimulus–stimulus associations.

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