Cutaneous constitutive nitric oxide synthase activation in postural tachycardia syndrome with splanchnic hyperemia.
نویسندگان
چکیده
Models of microgravity are linked to excessive constitutive nitric oxide (NO) synthase (NOS), splanchnic vasodilation, and orthostatic intolerance. Normal-flow postural tachycardia syndrome (POTS) is a form of chronic orthostatic intolerance associated with splanchnic hyperemia. To test the hypothesis that there is excessive constitutive NOS in POTS, we determined whether cutaneous microvascular neuronal NO and endothelial NO are increased. We performed two sets of experiments in POTS and control subjects aged 21.4 ± 2 yr. We used laser-Doppler flowmetry to measure the cutaneous response to local heating as an indicator of bioavailable neuronal NO. To test for bioavailable endothelial NO, we infused intradermal acetylcholine through intradermal microdialysis catheters and used the selective neuronal NOS inhibitor l-N(ω)-nitroarginine-2,4-L-diamino-butyric amide (N(ω), 10 mM), the selective inducible NOS inhibitor aminoguanidine (10 mM), the nonspecific NOS inhibitor nitro-l-arginine (NLA, 10 mM), or Ringer solution. The acetylcholine dose response and the NO-dependent plateau of the local heating response were increased in POTS compared with those in control subjects. The local heating plateau was significantly higher, 98 ± 1%maximum cutaneous vascular conductance (%CVC(max)) in POTS compared with 88 ± 2%CVC(max) in control subjects but decreased to the same level with N(ω) (46 ± 5%CVC(max) in POTS compared with 49 ± 4%CVC(max) in control) or with NLA (45 ± 3%CVC(max) in POTS compared with 47 ± 4%CVC(max) in control). Only NLA blunted the acetylcholine dose response, indicating that NO produced by endothelial NOS was released by acetylcholine. Aminoguanidine was without effect. This is consistent with increased endothelial and neuronal NOS activity in normal-flow POTS.
منابع مشابه
Cutaneous Constitutive Nitric Oxide Synthase Activation in Postural Tachycardia 1 Syndrome with Splanchnic
Cutaneous Constitutive Nitric Oxide Synthase Activation in Postural Tachycardia 1 Syndrome with Splanchnic Hyperemia 2 3 Julian M. Stewart*, Abhinav Nafday, Anthony J. Ocon, Courtney Terilli*, Marvin S. 4 Medow*. 5 6 Department of Pediatrics* and Physiology†, New York Medical College, Valhalla, NY 7 New York Medical College, Valhalla, New York 8 9 Stewart Short Title: Constitutive NOS in POTS 1...
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متن کاملCutaneous neuronal nitric oxide is specifically decreased in postural tachycardia syndrome.
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Prior work demonstrated dependence of the change in blood pressure during the Valsalva maneuver (VM) on the extent of thoracic hypovolemia and splanchnic hypervolemia. Thoracic hypovolemia and splanchnic hypervolemia characterize certain patients with postural tachycardia syndrome (POTS) during orthostatic stress. These patients also experience abnormal phase II hypotension and phase IV hyperte...
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عنوان ژورنال:
- American journal of physiology. Heart and circulatory physiology
دوره 301 3 شماره
صفحات -
تاریخ انتشار 2011