Detail of "16178-48-6"

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Antagonism by methylxanthines of purine nucleotide- and dipyridamole-induced inhibition of peristaltic activity of the guinea pig ileum

Antagonism by methylxanthines of purine nucleotide- and dipyridamole-induced inhibition of peristaltic activity of the guinea pig ileum. Okwuasaba, Francis K.; Hamilton, John T.; Cook, Michael A. (Dep. Pharmacol., Univ. West. Ontario, London, Ont., Can.). Eur. J. Pharmacol., 43(2), 181-94 (English) 1977. CODEN: EJPHAZ. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacodynamics) Section cross-reference(s): 13 The effect of the methylxanthines aminophylline (AMI) [317-34-0] and theophylline (I) [58-55-9] on the responses to the purine nucleotides, dipyridamole [58-32-2], catecholamines and papaverine-HCl [61-25-6] on pressure-induced peristaltic activity of the guinea pig ileum has been studied. ATP disodium [987-65-5], ADP disodium [16178-48-6], and adenosine [58-61-7] produced concn.-dependent inhibition of peristaltic activity in non-treated, reserpine- or 6-hydroxydopamine-pretreated prepns.; the relative potencies in descending order were ATP .gtoreq. ADP > adenosine. This inhibition of peristaltic activity by the purine nucleotides was antagonized by low concns. of the methylxanthines and this effect was reversible at all concns. tested. The antagonism by I (5.0 .mu.M) appeared competitive in nature. In contrast, peristaltic activity inhibited by noradrenaline bitartrate [51-40-1], isoprenaline sulfate [299-95-6] periarterial nerve stimulation (PNS) or papaverine was unaffected by the presence of the methylxanthines. Dipyridamole (5-10 .mu.M) produced an inhibition in the late phase of the peristaltic activity, while lower concns. (0.5-1.3 .mu.M) potentiated the inhibitory response to ATP, ADP and adenosine without influencing the responses to noradrenaline, isoprenaline, PNS or papaverine. The methylxanthines selectively antagonized the inhibitory effects of dipyridamole alone or in combination with the purine nucleotides. It is proposed, that AMI and I exert a selective action on a specific ATP-receptor and that I may be a competitive antagonist of the purine nucleotides on peristaltic activity of the guinea pig ileum. Since 100-fold greater concns. of AMI or I are required to inhibit this prepn. by inhibition of phosphodiesterase, it is highly unlikely that the inhibition of peristalsis by dipyridamole and the subsequent blockade by low concns. of the methylxanthines involves the 3',5'-cyclic AMP pathway. Furthermore, the parallelism obsd., between the effect of the methylxanthines on the inhibitory responses obtained with dipyridamole and the effects of ATP, ADP and adenosine, supports the hypothesis that non-adrenergic, non-cholinergic inhibitory neurons releasing a purine nucleotide as the neurotransmitter contribute to the descending inhibition obsd. during peristalsis.

The response of lymphatic smooth muscles to vasoactive substances

The response of lymphatic smooth muscles to vasoactive substances. Ohhashi, Toshio; Kawai, Yasuaki; Azuma, Takehiko (Dep. Physiol., Shinshu Univ. Med. Sch., Matsumoto, Japan). Pfluegers Arch., 375(2), 183-8 (English) 1978. CODEN: PFLABK. ISSN: 0031-6768. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Contractions of isolated bovine lymphatic smooth muscles were induced by serotonin creatinine sulfate (I creatinine sulfate) [971-74-4], PGF2a [551-11-1], dl-noradrenaline-HCl (NA) [55-27-6], histamine-2HCl [56-92-8], dopamine-HCl [62-31-7], and acetylcholine chloride (ACh) [60-31-1]. The smooth muscles were particularly sensitive to I. Excepting PGF2a, no other substances were as potent as I. The majority of I receptors seemed to be the D receptors. The decreasing order of the contractile responses was as follows: I > PGF2a > NA > histamine > dopamine > ACh. The contractile response to ACh was obsd. only in specimens involving a valvular region. In the lymphatics, there may be 2 kinds of receptors for catecholamines, i.e. a and b receptors, and the stimulation of the former induces smooth muscle contraction and that of the latter relaxation. Relaxations of lymphatic smooth muscles were induced not only by isoproterenol-HCl [51-30-9] but also by adenosine [5682-25-7] and adenine nucleotides. The decreasing order of the relaxant responses was as follows: isoproterenol > adenosine > ATP di-Na salt [987-65-5] > ADP di-Na salt [16178-48-6] > dibutyryl cyclic AMP Na salt [19436-29-4] 3 AMP di-Na salt [4578-31-8]. The relaxant responses to adenine nucleotides tended to decrease with decrease in the no. of high energy phosphates.